Do you have to get off campus housing? Is it hard to secure? What is the average cost? How far is it from the school, and does it have air conditioning?

After first semester, yes you do. The dorms are only large enough for first semester students. It's not hard to get, and in fact a studio is cheaper than the dorms. Generally they have AC, and can be all over the island - some places are nearby (the bottom), some are on the other side of the island (2 miles away). For the far away sites (lower Hells Gate) you pretty much need a car.