Hi, I've been a member of this forum for a couple of weeks or so, I'm not sure if I have posted anything yet. I recently bought a BP, and I have a few questions. I keep other herps, and have for years, but this is my first snake.

So, I discovered that my BP not only did NOT eat when they said it did at the pet store (yes I know, I should have known better, but this particular fellow had always been very knowledgeable, seems to truly care about the animals, and seemed to be very honest), it had apparently not eaten for some time. This became clear to me after seeing and handling some healthy ones that some owners had brought into the other LPS. My snake is very thin, and has been quite skittish. I waited almost a week to feed him (just a general reference, I do not know the snake yet, I want him to be settled before anyone probes him), and he readily took the mouse, but ate it backwards (any reason behind this? or do I have a less than intelligent snake?). It kept getting hung up on the feet, spitting it out, and trying again. It always went for the back end though... Is that something they normally do? Once it finally got it past the feet, there was no trouble getting it down. I put the snake back into the habitat, and it went into it's hide to digest. Everything was fine, and the snake shed the next day (the shed was almost in one piece, there was one part towards the back that was just ripped a bit, and the part under the throat was a separate piece. there seem to be a few different looking scales on the head and some down the body, are these scales that didn't shed or is there something that might be wrong? It is individual scales, rather than pieces of skin, I'm new to this, and reading doesn't always help as much as asking questions). The day after that, the snake defecated. That all seems normal to me, based on my limited experience and what I have read (I know they don't shed every time they eat, I knew the snake was going to shed before I fed it because it's eyes got milky); the thing I don't understand is that my snake looked fatter BEFORE I fed it than it does now. I have a water dish that I change every day, and I mist every day or two to keep the humidity around 60%. Should my humidity be higher (I believe I have read 60 is appropriate)? I have done what I have read to do to check for dehydration, pinch the skin on the back and see if it tents up, and it doesn't seem to. I really don't understand why my snake looks thinner since it has eaten than it did beforehand. Should I feed it sooner than a week to try to get the weight up? Maybe after five days? I seem to remember reading that that was appropriate for underweight snakes. Should I offer more than one mouse? I don't have a scale at the house, so I can't post the weight, but he is about 30 inches long (I measured the shed skin, I can't get it to stretch out straight to measure it, and I'm not comfortable enough to try with a string yet.), how big around should a snake like that be? The snakes I handled at the pet store that the owners brought in were much shorter than my snake and definitely fatter.
I tried to prepare before I bought the snake, but I feel like I don't know what I am doing as much as I would like. Any help will be greatly appreciated.