Standing for Shira:
The custom is to stand for the reading of Shira.
There is dispute amongst Poskim as whether one is to read Zeicher Amalek or Zecher Amalek. Practically one is to read both dialects. By the reading of Parshas Zachor [and Parshas Ki Seitzei] one reads first Zeicher and then Zecher. By the reading on Parshas Beshalach and Purim one reads first Zecher and then Zeicher. The Chabad custom is to repeat only the word Zeicher and Zecher. Others have the custom to repeat the entire verse. [By Parshas Beshalach and Ki Seitze one is to repeat the words Zecher-Zeicher/Zeicher-Zecher in both Shevii and the Haftorah.]
The custom is to eat buckwheat on Shabbos Shira.
It is permitted for one to feed home and farm animals, food and drink, if they are dependent on him for their food. It is however forbidden to feed home and farm animals if they are not dependant on him for their food. Thus it is forbidden to feed bees, or pigeons. It is forbidden to even simply place food in front of them. It goes without saying that it is forbidden to feed wild animals or birds.
Shabbos Shira: Some are accustomed to place food in front of animals on Shabbos Shirah, [even if the animals are not dependant on people for their food]. However based on above doing so is incorrect being that these animals are not dependant on people for their food. [Practically one is not do so, or even allow children above Chinuch to do so. Rather one who wants to honor the custom is to set up food for the animals from before Shabbos. Likewise one is to explain to children the importance of being merciful to animals.]
 Sefer Haminhagim p. 31; Luach Kolel Chabad
 Shaareiy Halacha Uminhag 2/288; Ketzos Hashulchan 84 footnote 22 and glosses to volume 3 (p.74b)
 This dispute is recorded in M”B 685/18; The Rebbe in Shaareiy Halacha Uminhag ibid writes his source is from the Mesorah; Some Poskim rule the main Nussach is with a Tzeirei. [Bitzel Hachachma 6/50; Piskeiy Teshuvos 685/9] Others rule the main Nussach is with a Segal. [Maaseh Rav 134 that so was the custom of the Gra; Ketzos Hashulchan 84 footnote 22; In the glosses to volume 3 (p.74b) he proves that this was also the opinion of the Tzemach Tzedek] In conclusion the Rebbe and Ketzos Hashulchan ibid rule that by Beshalach the main Nusach is with a Tzeirei while by Ki Seitzei the main Nussach is with a Segal. Nevertheless we still read both Nuschaos as will be explained.
The saying of the Toras Chesed: The Ketzos Hashulchan ibid quotes that the Toras Chesed stated regarding this dispute “Zecher, Zeicher, the main thing is to blot them out properly”.
 M”B ibid; Ketzos Hashulchan ibid in name of Toras Chesed; Rebbe ibid
The Ketzos Hashulchan ibid writes that those which are meticulous would read it one time with a Tzeirei and one time with a Segal. By the reading of Beshalach and Ki Seitzei [when the Parsha is read twice, once for Shevii and a second time for Maftir] they would read it one way by Shevii and the second way by Maftir. By Purim and Parshas Zachor [in which the portion is only read once] they would repeat the verse twice. In the glosses to volume 3 (p.74b) he concludes that this is the custom, to read both Zeicher and Zecher, and so was the directive of Rav Shneur Zalman of Lublin, the author of Toras Chesed. To note however that there he mentions that the Baal Korei in Lubavitch stated they by Beshalach they would read only with a Tzeirei, and by Ki Seitzei only with a Segal.
 So concludes the Rebbe ibid and Ketzos Hashulchan ibid
The reason behind this order of Zeicher/Zecher: This ruling is based on the Sefer Boneh Yerushalayim which is Meyuchas to the Alter Rebbe. There it states that by Beshalach the main Nussach is with a Tzeirei while by Ki Seitzei the main Nussach is with a Segal. [Nevertheless we still read both Nuschaos as ruled the Toras Chesed.] Thus by Beshalach we first read it with a Segal [Zecher] and then with a Tzeirei [Zeicher], as the second word read is viewed as a correction and is the main Nussach. By Ki Seitzei we follow the opposite order as the word Zecher is the main Nussach.
 See Piskeiy Teshuvos 685/9
 Otzer Minhagei Chabad p. 18 unlike the custom recorded in Ketzos Hashulchan 85 footnote 22, and the supplements in the back of the Sefer, that one is to read Zeicher by Shevii and Zecher by Maftir.
 Sefer Haminhagim p. 72; Hayom Yom 17th Teves; Eating whole grains on Shabbos Shira is mentioned in Bach 208 “Tosafus”
 As they eat food from the field and are not dependant on the owner for food. [ibid]
 As the Sages only permitted troubling oneself on Shabbos for animals if the animals are dependant on oneself for their food. [ibid]
 So rules M”A.
Nevertheless some justify the custom on the claim that since their intent is for a Mitzvah, in order to repay the birds which sang Shirah by Kerias Yam Suf, therefore they may do so. [Tosefes Shabbos 117; Minchas Shabbos; brought in Ketzos Hashulchan 131 footnote 5; Aruch Hashulchan 324/3; Nemukei Orach Chaim 324 states it is an accepted custom from the Holy Tzadik Reb M”M of Rimnav, to give the birds crumbs on Shabbos Shira in reward for them having eaten the leftover Man which Dasan and Aviram cunningly spread out on Shabbos night to make it appear as if the Man fell on Shabbos. He then goes on to defend the custom based on Halacha.]
 Shaar Halacha Uminhag 1/149
Other Opinions: Ashel Avrahahm Butchatch 167/6 allows children to do so being that it is not a complete Shvus.
 Shaar Halacha Uminhag 1/149