What to wear to class - Gift for Host Family

Hello,
Later this summer I'll be going to Japan to study Japanese language at a University, but I was unsure about what would be acceptable clothing to wear to class.
Here at my Uni in the US jeans or sweats and a t-shirt are pretty standard, are Japanese University's the same?
I had heard that the Uni's there are a bit more formal?

Also, my Uncle has arranged for me to stay with a Japanese Host Family for a week while I'm there - What would be a good gift to bring?
Would foods such as locally made jams etc, be o.k?
Thanks!

I would say jeans or chino pants and a T-shirt should be fine. I would avoid sweats initially - just see what your classmates are wearing, if you see sweats you can "dress down" to sweats too, if you want. It can get quite hot and humid, so you might consider chino pants (a bit lighter fabric) instead of jeans.

Yes, locally made food would be fine :)

I think, and this is just my understanding, that for the most part, people have to commute to Japanese universities, which is why they dress in more than just their pajamas (where in the states, students tend to live about a 10 minute walk from their classes and don't have to be seen by the outside world).

Is it appropriate to wear capris to class if it's particularly warm?

Also - I have heard the Japanese schools don't typically have air conditioning. Does this apply to the universities as well?

Students are very casual just like anywhere else. Just wear comfortable clothing - it's going to be very hot in summer.
There's a power saving movement underway so some places may not be using as much air-conditioning but I cannot imagine staff & students putting up with unbearable conditions because nobody go to class.

Generally speaking Japanese dress casually but more sharply than their western counterparts. Just wear a skirt and simple top at first until you get the feel for what everyone else is wearing.
For staying with a host family, it's highly likely that they will take you out to some fancy place at least once, so bring at least one nicer outfit and high heels. Regarding a gift for them, generally you want to bring something that represents where you are from. Maybe bring a small gift for each member of the family, and one gift for the family as a whole. Nothing extremely expensive is necessary.
They will also return the favor and if you give very expensive gifts it puts the pinch on them to give something of equal or slightly higher value.

Some ideas are: picture books or calendars, ashtrays, coasters, chocolates, fragrant bath salts, t-shirts or jackets of sports teams, BBQ sauces; dijon or dark mustards, unique salad dressings, jams or other preserves, soap or shampoos, lotions, nuts, dates, dried fruits, flavored coffees and teas, keychains, postcards, mugs, and so on.
By the way, 4 and 9 are unlucky numbers in Japan, so if possible try to avoid any gift sets with just those numbers. An ideal gift arrangement is something for each of their senses, like something nice to taste, smell, see, and so on. Taking all foods is nice but then there's nothing left after eaten and you are gone.