Sounds like you and I have a lot in common, bud.
I powerlift, I'm 19, I live in the dorms, I spend a lot of time in class.
Work on standing up straight, correct your posture when sitting in desks (move your ass all the way to the back of the seat) keep your shoulders back and straight.
I find sleeping on my back is the best way to reduce tension in my back on the shitty dorm beds, I mean, I have a pad on the bed but it doesn't make up for shitty mattresses :D.
And make sure you STRETCH it.
If it doesn't improve you could seek professional help with it.
And hit up the dining halls often, pre-prepared food is awesome.
And Amsterdam, if they're arching because of shitty form they'll eventually stop or learn how to do it right.
I don't think arching while benching, even with crappy form, creates much chance for injury.
I mean, they might end up pinned under the weight because they're not stable (When you arch you pull your shoulder blades together to provide a stable surface from which to push) but in all probability, if they end up pinned it's probably just because they're weak.