1. I wouldn't recommend unite, but if you really want it, then yes you apply through the uni. Accom applications open July and offers are made in September I think. Go to Bristol.ac.uk/accommodation for the information you need. It's not laid out in an especially user-friendly way, but it's there.
2. Like basically everywhere, the people at Bristol will have different personalities... There will be some who are suited to you, and some who aren't... So this is a bit of a weird question as there is no one 'type' of person that goes to Bristol.
3. From what I've heard, the English course seems to be good and people are really enjoying it.