What is one obligated to read?
One is obligated to read all the pesukim in the Parsha two times and to read the entire Targum Unkulus of that Parsha. [see footnote regarding reading other commentaries instead of Targum] Likewise every G-d fearing Jew is to also read the entire commentary of Rashi of that Parsha. If one does not understand the words of Rashi then he is to read another commentary which is written in his language. [Practically it is the Chabad custom to learn every day the daily Torah portion with Rashi, however not to repeat this learning of Rashi when doing Shnayim Mikra.]
A verse which does not contain a Targum translation: Any verse which does not contain a translation in Targum is to be read three times.
The Haftorah: Although from the letter of the law there is no obligation to read the weekly Haftorah to oneself each week, nevertheless the custom is to do so. [On a Shabbos that there are two Haftoras for that week, such as the Shabbos of the 4 Parshiyos, Shabbos Rosh Chodesh, Shabbos Machar Chodesh, Shabbos Chanukah, then one is to read both the Haftorah of the weekly Parsha and the Haftorah which will be read in Shul. [see footnote] On Shabbos Chol Hamoed Sukkos and Pesach one is to read to himself both the Haftorah of the Parsha of the coming week and the Haftorah which is read that Shabbos.]
Reading Vezos Habracha on Erev Simchas Torah:  On the eve of Simchas Torah [i.e. Shemini Atzeres in the Diaspora; Hoshana Raba in Eretz Yisrael] one is to read the Parsha of Vezos Habracha, Shnayim Mikra Vechad Targum.
Is one who cannot read Hebrew obligated to read Shnayim Mikra in translation to his language?
May one read Shnayim Mikra of Vezos Habracha prior to Hoshana Raba?
Must one read Shnayim Mikra of the Maftir of the four Parshiyos or Rosh Chodesh?
Q&A relating to one who traveled from Eretz Yisrael to the Diaspora or vice versa
If one will be traveling from Eretz Yisrael to the Diaspora in a week that in Eretz Yisrael the weekly parsha is read while in the Diaspora that Shabbos coincides with Yom Tov, is he to read Shnayim Mikra of the Parsha of Eretz Yisrael?
No. One is to do Shnayim Mikra of that Parsha the next week after Yom Tov ends in the Diaspora.
One is to read the Shnayim Mikra of both Parshiyos, the one which he is now missing in the Diaspora and the one which he will now hear in Eretz Yisrael. [If he returns to the Diaspora after Shabbos he is not required to repeat the Shnayim Mikra of the Parsha that was read in Eretz Yisrael and is now being read in the Diaspora.]
Sparks of Kabala-The inner meaning behind reading Targum:
The Shlah Hakadosh [p. 128] writes that on Erev Shabbos the level of Kelipas Nogah requests to be elevated into Holiness. This elevation occurs through the reading of Targum Unkulus. This is because Unkelus was a convert and a convert represents that exact elevation, as a gentile is Kelipa which through conversion entered into holiness.
 See Halacha 4 Q&A regarding reading the verse of Shema Yisrael twice.
 Regarding if one is to read Targum versus another commentary the following is the ruling of Admur in the Shulchan Aruch [285/2]:
First Opinion: Targum Unkelus explains many matters which cannot be understood from the simple reading of the verses. Hence one cannot replace reading the Targum with reading a translation of each word in his language. Furthermore some opinions [Hagahos Maymanis Tefila 13/300 in name of Geonim] say the reading of Targum Unkelous merited taking precedence over any other commentary being that it [or its language of Aramaic-see L.S. Vol. 21 P. 447] was given to Moshe at Sinai [as is evident from the Torah using the words “Yegar Shadusa” in Aramaic – Beireishis 31/47], and hence one may only fulfill his obligation through reading the Targum.
Second Opinion: Others [Michaber 285/2] rule that if one reads a commentary on the Torah [irrelevant of language] which explains each and every word of the versus more than does the explanation of Targum, then reading this commentary is better than reading the Targum. Likewise according to this opinion it is better to read the Torah twice and then a third time to read the entire Torah with the commentary of Rashi, then it is to read Targum. The reason for this is because Rashi is based on the fundamentals of the Talmud, and hence explains more than does the Targum. [However even according to this opinion it does not suffice to read the Torah twice and then to go straight to the commentary of Rashi being that Rashi does not explain every verse or word and one is thus lacking the third reading of some words and verses. Hence this option is only valid if one goes back and reads the entire Parsha a third time with Rashi. (Kuntrus Achron 1; however see M”B 285/5)]
Practically the main opinion is like the latter opinion, although a G-d fearing Jew is to read both Targum and Rashi. [285/2]
Summary of ruling of Admur: Based on above it seems that the summary of this Halacha should be as follows: It is best for one to read the Parsha three times with commentary of Rashi [the main opinion], although a G-d fearing Jew should also read Targum. So summarizes Kitzur Halachos 285/3. However the Ketzos Hashulchan 72/1 summarizes as written above that first and foremost one is to read the Targum and it is only that a G-d fearing Jew should also read Rashi. Perhaps the reason for this is because according to both opinions one fulfills his obligation with Targum, while with Rashi it is a dispute as explained above. Now, although the main opinion follows that reading Rashi is better, since according to the other opinion one does not fulfill his obligation by doing so, it is ruled that one is to read Targum, and if one is G-d fearing then he should also read Rashi in order to fulfill his obligation the best possible way according to the main opinion. This understanding can also be understood from the wording of Admur in his concluding ruling that “….is to read Targum and also Rashi” hence giving precedence to Targum and making Rashi only secondary. This explanation is unlike the understanding of Kitzur Halachos ibid which gives precedence to Rashi over Targum.
The Kabalistic perspective: Based on Kabala [see below “Sparks of Kabala”] one must read Targum and may not replace it with another commentary. Hence if one does not have time to read both Targum and Rashi he is to read Targum. [Beir Heiytiv 285/2; Shaareiy Teshuvah 285/3 in name of Bircheiy Yosef]
Other Opinions: The Rashal rules that if one is unable to read both Targum and Rashi he is to rather read Rashi. [Brought in Shaareiy Teshuvah ibid]
- The practical Custom: In conclusion, practically the Chabad custom is, as written above, to read Targum and only in addition to read Rashi if one so chooses. [Sefer Haminhagim p. 49 [English]; Hayom Yom 30th Sivan]
- To summarize the requirements from the letter of the law: From the letter of the law one can either choose to only read Targum [which all agree fulfills one’s obligation] or only read a commentary which explains every word, or read the Mikra a 3rd time with Rashi. [As rules the second opinion which is the main opinion.] A G-d fearing Jew is to read both the Targum and Rashi. If one will only be able to read either Targum or Mikra a third time with Rashi, it is better to read Targum [as explained above].
 See above footnote for background behind this ruling.
Seemingly Admur singles out learning Rashi over any other commentary due to that Rashi is based on the Talmud and hence is better than other commentaries. To note that according to the opinions which allow reading commentary in place of Targum Admur placed the commentary of Rashi in the plain Halacha and only added other commentaries in parentheses, hence implying that there is room to argue that even according to this opinion which allow other commentaries perhaps they allow only Rashi and not others. To note from Sefer Haminhagim p. 39: The commentary of Rashi on the Torah is the wine of the Torah, it unlocks one’s heart and reveals one’s innate love and fear of G-d. Studying a section of Chumash with Rashi everyday activates the light within the soul and reveals the soul. This is a glow of the revelation of Moshiach.
 So is implied from Sefer Haminhagim ibid that does not mention Rashi as part of being Mavir Sedra. Logically this is because we already fulfill our obligation of Rashi with the reading done during the week. To note however from Igros Kodesh 13 p. 425 that learning the daily Chumash with Rashi is independent of Shnayim Mikra. Perhaps however that means that even without the obligation of Shnayim Mikra it would be done, however once it is done it too counts for one to fulfill the obligation of G-d fearing Jews to learn Rashi.
 Such as the versus of the names of the Shevatim.
 In order so one be familiar with the Haftorah in case he is called up for Maftir.[ibid] This custom is likewise recorded in Sefer Haminhagim p. 49 [English]; Hayom Yom 30th Sivan.
Nevertheless from the fact that it is our custom to read all the Haftoras of a coming week, even the one which will not be read in Shul such as when Rosh Chodesh falls on Shabbos, makes it evident that this reason alone cannot be the full reason behind reading the Haftorah. This would likewise apply even in accordance to the ruling of Admur in the Shulchan Aruch [see next footnote] that only the Haftorah which will be read in Shul is to be read, as in conclusion Admur rules that when Sos Asis will be read as Haftorah many consecutive weeks one is to read to himself on the second and onward Shabbosim the weekly Haftorah rather than Sos Asis.
Custom to read also the Haftorah with Targum: Some have the custom to read the Haftorah Echad Mikra Vetargum. [M”A 285/8] This is not the Chabad custom.
 This ruling follows the custom mentioned in Sefer Haminhagim p. 49 [English]; Hayom Yom 30th Sivan; So rules also Kneses Hagedola; Moreh Betzba
The ruling of Admur in the Shulchan Aruch: In a case that there are two Haftoras that week one is only to read the Haftorah which will be read in public and not the Haftorah of the weekly Parsha. The simple reason behind this ruling is as Admur explained earlier that the entire custom to read the weekly Haftorah is only in order so one be prepared in case he is called up to read it. Hence in a week that it is not being read there is no custom to review it. Nevertheless our custom is to review all the applicable Haftoras. See previous footnote.
 Hisvadyus 1985 Vol. 1 p. 351
 As one has already read, or will read, these portions within their weekly Parsha.
 After [midday] of Hoshana Raba. We however do not read Shnayim Mikra of Vezos Habracha on the night of Hoshana Raba [after the Tikkun] as is the custom of others. [Sefer Haminhagim p. 145 English, unlike the custom brought in Ketzos Hashulchan 72 footnote 4; So concludes also Peri Megadim A”A 285/10 that although many have the custom to read on the night of Hoshana Raba, it is best to read it on Erev Simchas Torah, and so concludes Ketzos Hashulchan ibid.]
Other customs: Many in Eretz Yisrael are accustomed to read Shnayim Mikra of Vezos Habracha on the night of Hoshana Raba after completing the reading of Mishneh Torah.
 As Vezos Habracha is read on Simchas Torah and has not yet been read during the year, hence it is similar to all weekly Torah portions which must be read Shnayim Mikra prior to their being read. [ibid]
 Seemingly one is obligated to read the verses in his language, as is the ruling regarding one who does not understand Rashi that he is to read a commentary in the language which he understands. Vetzaruch Iyun as in this case he is still lacking the concept of Mikra, and it is merely like he is reading Targum three times. Vetzaruch Iyun Lemaaseh
 Pashut as doing so is no different than reading it in the Hebrew original.
 Ketzos Hashulchan 72 footnote 3.
The doubt: Seemingly there is room to say that according to the Poskim which allow completing a Parsha until Shemini Atzeres, the entire year is considered the time for that years Parshiyos, and hence Bedieved one is Yotzei no matter when it was read that year. Vetzaruch Iyun.
 Kaneh Bosem 1/16
 As is the law regarding the sections read on Yom Tov, being that these sections were, or will be, read in their applicable Parshiyos.
 Brought in Piskeiy Teshuvos 285/3
 For a thorough analysis on this matter-see Betzeil Hachachmah Vol. 1/2-8
 This can occur when the 2nd day of Pesach or Shavuos falls on Shabbos in the Diaspora and hence no Parsha is read, while in Eretz Yisrael the regular weekly Parsha was read. If one travels that week to the Diaspora he will be hearing the same Parsha that he heard the previous Shabbos in Eretz Yisrael.
 Ketzos Hashulchan 72 footnote 3
 This ruling is evident from Admur 285/9 which does not require one to read Shnayim Mikra of the Yomim Tovim sections prior to each Yom Tov being that it was already read or will be read in its related Shabbos portion. Hence the same logistics apply here and there is no need to repeat Shnayim Mikra.
 Piskeiy Teshuvos 285/2
 Such as one who travels during Chol Hamoed Pesach, or the week of Shavuos and the second days in the Diaspora coincide with Shabbos.
 Piskeiy Teshuvos 285/2
 Such as one traveled to Eretz Yisrael the week after a two day Shavuos or Pesach which coincided with Shabbos, in which case Eretz Yisrael is one Parsha ahead in its reading.
 Ketzos Hashulchan 72 footnote 3