First I'am glad you have her. It sounds like she has had a very bad life. First at 2.5 feet she can eat larger prey, I would offer her a full size mouse, once a week. For the next several weeks, however as she gets use to a weekly feeding schedule, you will want to try and get her to eat a small rat. It may take a while to get her to switch over. So if she does not eat the rat give her a full size mouse. The biggest thing is to get her to eat as, from your description she is way under weight. As far as the shedding problem humidity is key. I keep my snakes in a rack system so humidity is not a big problem. So I will let someone else that has experience with keeping Bp's in an aquarium,give you some advice. Also welcome to the BP forum, I wish you the best with your new pet. Let us know how things are going with her.