Bredli pythons tend to be very good eaters. If you can use size equivalent rats, I'd go that route. I am a big advocate of quail. If you can mix quail and rats for variety you'll be in good shape.
I have introduced rabbits to the diet as well.
I agree with the above post regarding floor heat. Nick and Justin mention in the books they prefer RHP's. After a certain point in the evening, I never see the snakes on the floor. I do see them in a floor hide during the day however.
A good RHP will create a VERY hot spot on a perch or shelf below it. I prefer perches because they don't completely keep the heat off of the floor directly below. You still have a floor hot spot that is cooler than the perch hot spot and then the floor opposite of the panel sits at the ambient temp you want. Perches that span the cage will offer various climate gradients.
The advice above is geared more toward your adult/final setup.
Go looking for your branches now, then you will have a lot of time to treat them if you need to. Let them sit out in the winter next year if you are not planning the final caging for a while. Cut or find large branches so you can re-cut and size them to fit the final cage.
Get a picture thread going when you get the snake and have it comfortable.
JMCrook has some great starter cage ideas if you have time to check out some of the threads he posts.