Drinking wine and other significant beverages:
Settling oneself over the beverage: One who settles himself down to drink wine, or other beverage of significance of which is it is common to settle oneself upon, is obligated to drink it in the Sukkah. However the blessing of Leisheiv Basukkah is not said upon drinking it, [with exception to Kiddush and Havdala in which it is said].
Due to this, that no blessing is said, it is proper not to drink wine, or other significant beverages, in a settling manner in a Sukkah which one has not, and does not plan to, say in it Leishiev Basukkah that day. [Hence when invited to someone else’s Sukkah to settle with him and drink wine, one is to eat a Kebeitza of Mezonos in order so the blessing of Leisheiv Basukkah cover the wine.] However when eating in a Sukkah that one has said Leisheiv that day, or plans on doing so, then there is no need to refrain from drinking the wine, as it is already included in the blessing of Leishev which was or will be said that day.
Drinking the beverage casually: It is permitted from the letter of the law to drink wine or other significant beverages in an unsettling manner outside of the Sukkah. This applies even if one drinks a lot more than a Revius of the beverage. However one is stringent to not even drink water outside the Sukkah is blessed.
Kiddush is to be made inside the Sukkah. The blessing of Leishiev Basukkah is said prior to drinking the wine. However on the 1st night of Sukkos it is said before the blessing of Shehechiyanu, while on the 2nd night it is said after the blessing of Shehechiyanu. [During the Kiddush of day the blessing of Leisheiv is said after the blessing of Hagafen, prior to drinking from the wine.]
May one make Havdala outside a Sukkah for an ill patient which cannot come into the Sukkah?
If the patient is unable to make Havdala himself then one may do so for him, although he should try to drink only the majority of a Revius, as opposed to a full Revius.
 639/12; so rules also M”B 639/13 Biur Halacha “Veyayin”; Kitzur SH”A 135/7
Other Opinions: It is evident from the Rama that it is permitted to drink wine and any other beverage outside the Sukkah even if one settles himself over it. [Rama 639/2; M”B 639/13]
Proof for opinion of Admur: The Gemara [Sukkah 28b] says that one is obligated to eat, drink, and sleep in the Sukkah. This ruling is brought down in the Shulchan Aruch 639/2 and in Admur 639/4. Now, if there are no drinks that are obligated to be drunk in the Sukkah then what is the meaning behind this ruling regarding drinking. Hence we must conclude that significant beverages which one settles on is obligated to be drunk inside the Sukkah. [Biur Halacha “Veyayin”]
 639/12 and 15
The reason: as A) It is already exempted within the blessing of Leisheiv which was said, or will be said, in that same Sukkah over Mezonos or Hamoitzi. [639/12] and furthermore B) Even in a Sukkah where one does not plan on eating Mezonos or Hamoitzi there, and one has not yet done so, the blessing of Leisheiv should not be said merely over drinking the wine, despite that it is said on sleeping or spending time there, as there are opinions [see above footnote] which question whether a blessing of Leisheiv is to be said over the wine. [639/15]
 As will be explained next.
Other Opinions: The Mishneh Berurah [639/13] and Kitzur SHU”A [135/7] rule that although one is not to say the blessing of Leisheive Basukkah over drinking wine in a settling manner, nevertheless in order to fulfill the obligation like all opinions one is not to settle himself over wine or other significant beverage unless he drinks it within a meal or directly after eating a Kebeitza of Mezonos. [This implies that the M”B/Kitzur in essence rules that wine may require a Leisheiv Basukkah even when drunk in the same Sukkah that one has already said Leisheiv on that day, unlike the ruling of Admur in 639/12, hence he rules that one is to only drink it within a meal and not simply within a Sukkah that Leisheiv has or will be said in, as rules Admur. Possibly the reason for this ruling is because he views wine similar to bread or Mezonos which are significant on their own and are not secondary to any previous blessings said.]
 So rules Admur 639/12. However the Biur Halacha 639 “Yayin” he brings the Ritva which rules that a Revius is already defined as “settling down to drink”. Clearly Admur does not accept the amount of liquid consumed as the measuring factor in the definition of “settling”. Rather one must say settling refers to its simple meaning of spending time over the drink.
 Michaber/Admur 643/1; Rama 643/2
 Michaber/Rama 660/1, and so is implied from Admur 643/1
Other Opinions: The Bach; Rashal; Radbaz rule that on the second night as well the blessing is to be said before the blessing of Shehechiyanu. Practically each is to follow his custom. [M”B 661/2]
 Sefer Haminhagim; See Oatzer Minhagei Chabad 135. This ruling follows the ruling of the Kneses Hagedola and Levush. [Brought in Beir Heiytiv 661/1]
Opinion of Admur in Shulchan Arucha: In the Shulchan Aruch [643/3] Admur rules, as does the Taz, that Leisheiv is only said by Kiddush of night being that it contains the blessing of “Kiddush Hayom”. However by day, being that it only contains the blessing of Hagafen, it is not said by Kiddush bit rather by Hamotzi.
Opinion of M”B: The M”B [643/9] brings down both opinions and rules that one may choose like whom to follow.
The reason: As throughout the rest of the year one enters into his house to say Havdala, and one must live in his Sukkah as he does in his house. [ibid]
 Siddur Tehilas Hashem, based on directive of Rebbe and previous Rebbe. See Otzer Minhagei Chabad 186-188. This custom is also brought in Sheivet Haleivi 6/42 which writes that many have such a custom [although he himself does not rule this way, he defends the custom]. Luach of Harav Tuchinsky writes to say Leisheiv after Havdala.
The reason: This is similar to the ruling that Leisheiv is always said by Kiddush. Perhaps the reason for this is because when the drinking of wine is obligated for a Mitzvah it is considered significant enough to not be secondary to other blessings said on bread or Mezonos, and hence is given its own blessing of Leisheiv. [See Sheivet Halevy ibid which defends the custom based on that Havdala is “Kevius”; Piskeiy Teshuvos 639/10]
Other Poskim: There are those which are accustomed not to say Leisheiv by Havdala. [Sheivet Halevy ibid] Others say Leisheiv and make sure to eat a Kebeitza of Mezonos afterwards. [RSZ”A brought in SSH”K 58 footnote 103]
 Ruling of Rav Greenwald brought in Sheivet Halevy 6/42; Piskeiy Teshuvos 639/10 in footnote.
Seemingly this ruling would apply even in accordance to our custom as it is usual during the year to make Havdala near a patient in a case that they are ill. [See M”B 639/30 and Shaareiy Tziyon there!]
 Vetzaruch Iyun as by doing so one enters himself into a questionable after blessing, as well as that according to Admur 639/12 there is seemingly no relevance to the concept of a Revius to making ones drinking defined as Settling.