all valid questions. so let's talk about colleges.
u of t is split up into to a number of different colleges (new, st. mike's, university, innis, woodsworth, victoria, and trinity plus erindale@mississauga and scarborough campus). each one will have between 1000 and 5000 affiliated students and you my lucky little friend could be one of them! each college kinda has its own flavour of the week kinda deal, so yer best bet is to go check em all out if you have the time and chance. short of this, there ain't much i can say. different colleges are renowned for different things.
one of the considerations should be the rez and the meal plan. different colleges have a different style of rez. some will have you sharing rooms, some will have you in your own room and others still will have you living apartment style in no time. some college's will provide meal plans (which by the way tend to suck from what i've heard). but they're good if you're an idiot stick and can't cook for yourself.
your classes won't be at your college. repeat.....your classes will not be at your college. you can take classes in any of the campus buildings regardless of your college affiliation. this ain't high school. you'll be all over campus like a true metropolitan stumbling around, lost like a helpless puppy. somebody will help you find your classes. i promise.
if you dislike your college, tough crap. you're there for life!!! jokes. you can apply to transfer whenever you feel that irrepressible urge for adventure and travel (even if its just across the street).
that's that. all you need to know about the various campuses can be found somewhere on the u of t main site. surf.