You can feed your boa weekly, or bi-weekly but I would offer weekly. Not every snake is the same and appetites vary. For instance you and I eat differently, you may get hungry twice a day where as I get hungry once a day. Many things come into effect, so I say offer food weekly and stick to the same schedule. Boa's like a bit higher humidity, and I would let my temps hover in the mid 70's at night and about 86-87 during the day.

Depending on the current size of the boa, I would get a 48" long tank if it's anything around 4-5'. If it's smaller then I wouldn't do anything that size yet. Also the females are going to be larger than the males, so keep that in mind when selecting as well. Also if you're RTB is big enough to eat a rat over mice then do so, because rats are a healthier choice, just knock the rat out when you feed the snake. I used to take a pair of channel locks and I'd grab the rat by the tail and I'd nail him with the channel locks. It either killed them or knocked them out, that way you don't risk the rat biting the snake, Treating wounds aren't fun.