I would start with redtailboas.com for info and questions.
An AP T8 enclosure should house him for life, in fact it may be a bit big for a sub-adult but if you clutter it up with a lot of hides it will work.
I feed my sub-adult males every two weeks and adult males every three weeks. Prey items (rats) are no bigger than the boa's widest girth. A round boa is a fat boa, they should have a square body shape.
As for handling, I don't do it for a few days after they eat, and definitely not right after you handle the rabbit. I would try to find a way to keep the rabbit out of the reptile room, my boas have very strong food responses.