According to Chabad, ideally, men should not eat before Shofar. If this is difficult, or there is any concern that one will not be able to concentrate during davening, he may eat and drink (preferably not Mezonot). One should not be stringent if there are health concerns.
Avinu Malkeinu: Some have the custom to recite part of it verse by verse after the Chazzan, however, it is not the Chabad custom to do so. The words Roia Gzar are recited without pausing in between. It is customary to grant an Aliyah to the Ba’al Tokeiah and the Ba’al Musaf, unless they are being paid.
The Lubavitcher Rebbeim would say Yizkor discreetly between Haftorah and the Tekiot. Those without parents can choose whether to follow suit. Some have the custom to make Kiddush after Kriat Hatorah, before Tekiot. Ya’aleh Veyavo and both Horachamon’s are recited during Birchat Hamazon, even if it is already after Tzeit Hakochavim. Havdalah is recited without Besamim and candles.
