OK, silly questions, but how many towels, socks, etc. do you plan to send up? Enough to last one week, assuming that's how often they will do laundry?
I am also concerned about him bringing too much "stuff". His room is only 11 x 17, not a whole lot of space!
I talked to a friend yesterday about some of this (her DS is at the same school as my DS is attending ... just a year ahead) and her advice to me was not worry much about sheets. They'll likely get washed over holiday breaks, and not much more often than that. LOL. She said to definitely pack more than a couple of towels... because they'll only get washed when they start to stink

I didn't think to ask about socks/underwear. 10 days worth? is that too much?