Ideally, men shouldn’t eat before Shofar. If this is difficult, or there is any concern that one will be unable to concentrate during davening, he may eat and drink (preferably not Mezonos), as necessary. One shouldn’t be stringent if there are health concerns.
It is especially appropriate to go to Mikvah before davening.
The Chazanim should familiarize themselves in advance with the meaning of all of the Piyuttim and Tefillos – even if they already did so the previous year. Similarly, one should train his children regarding the order of davening beforehand, so as to minimize any distractions during davening.
Shir Hamaalos (after Yishtabach): It is not Chabad custom to open the Aron Hakodesh, nor to recite it verse by verse after the Chazzan.
When the Aron Hakodosh is opened during Chazaras Hashatz, it is not obligatory to stand, since the Sefer Torah is not being moved. Some have the custom to stand. [The Rebbe was not particular about this.]
At Shacharis, the paragraph of Misoid (at the beginning of Chazaras Hashatz) and the one that follows is recited by the Chazzan and not by the congregation.
The Rebbe would always stand for the Piyut beginning L’e-l Orech Din, recited in Shacharis on the first day and in Musaf on the second day.
Avinu Malkeinu: It is not our custom to recite it verse by verse after the Chazzan. 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.
A Bris performed at Shule is conducted before Tekios. A Bris performed at home is held after davening.
