sharing a room is one of those character building experiences that no matter if the roommate is good or bad, it is good for you. if your roommate turns out to be a total weirdo or creep or whatever, you can change roommates (at least at my school you could).
smoking in your room depends on the school. i went to a fairly strict school that was trying to crackdown on the whole party scene so i never smoked in my room. i got paranoid enough just being in the dorms high cause i coulda gotten in trouble just for that,thankfully i didnt.
i wouldnt recommend having a bong or a vape or anything big and/or nice because they are harder to hide and would be a bigger disappointment and $ loss if they got confiscated. bubblers are perfect, i had one a pocket size i kept all year rolled in socks in my sock door.walked by dickhead RA's with it too so it worked out fine.