You shouldn't handle your BP for at least twenty-four hours after they feed. It's usually all right then, but not for an extended period of time. They'll let you know when they're ready... mine curl up next to the heat immediately after eating and don't move for a day or so. As for getting frozen mice online... it is quite a bit cheaper, but you have to buy A LOT to save on shipping costs. If you buy quite a bit up front, the shipping really isn't that bad. I don't really have enough snakes to make it worth it right at the moment (especially with my baby still eating live).
I read on one forum (can't remember if it was here or not) that when the snakes got too big for the hoppers, they used them as snacks for the snakes... every couple of days or so. Hope this helps!