Answered by Shaykh Faraz Rabbani
1) During the khutba, when the khateeb mentions the Prophet’s name (salAllahu ‘alayhi wasalam) I learned that we are not supposed to say salawaat out loud but rather it is to be done silently in one’s heart, even if the ayah which makes salawaat waajib is read out. As well, during the du’a before the salaah of jum’ah the Hanafis are not to raise their hands in du’a and say “amin” out loud but in their hearts again. Is this correct?
2) Wearing clothes for prayer that one would not normally wear in public (e.g. clothes worn for sleeping) is of what degree of dislike (tanzih or tahrim)? In particular, I’m thinking of the situation where one wakes up for Fajr and prays in their pajamas.
3) Is there any dislike in wearing short sleeves for salaah (when no need necessitates its wearing)?

Walaikum assalam,
(1) Correct.
(2) Tanzihan. [Somewhat disliked, but not sinfully so.] (Ibn Abidin)
(3) It is somewhat disliked to pray with short sleeves, and also with rolled-up sleeves. In the latter case, it is best to un-roll them with slight movements if you realize it during the prayer. (Ibn Abidin)
Similar to this is if your kufi or cap falls off during the prayer; it is best to pick it up with slight movements.
Wassalam,
Faraz