Had a brief conversation with Rabbi Chaikin.
He said that:
-If it's a shul where the minhag is for B"M bochurim to wear a talis or for a bochur to wear a talis for getting an aliya or going to the amud, fine. Otherwise, we don't do that.
-Slichos talis, as mentioned above is not about kavod hatzibur. At any rate, he would not have a bochur daven slichos as al pi chassidus a bochur shouldn't wear a talis. He said he'd have to look it up. B'shas hadchak where there only bochurim, he didn't think they would wear a talis.
-As I expected, he said the ufruf is an exception as that's an aliya to prepare you for married life and is connected with being married, so you wear a talis.