Do the scales look like this?
If so, I don't know what causes it. It's just an anomaly I have been told. I have some that have it, others that don't. It's never seemed to affect their health or shedding though, so I quit worrying about it. LOL
Believe it or not, that snake really ain't THAT skinny IMHO. A little thin, but not really emaciated or anything. Boa should have a lean muscular body all the way down. Personally, I think a regular feeding schedule of every couple weeks would show a difference in just a couple months. Nice looking animal though. Hard to say, but it looks to me to have characteristics of BCC and BCI. May be a cross of the two.
I leave my hot spot on 24/7 and check it several times a day. You need to regulate it in some way, like a thermostat, or at minimum, a rheostat, so that it does not get too hot. Some of the UTH units have a rheostat built into them. But don't rely on the units readings by themselves. Get another temp unit like
this from wally world or something as an independent way of measuring temps for safety.
Water bowl should be big enough for the snake to soak in, if it wants to. Some soak, some don't. Humidity should be around 50-60 constant, with higher RH during sheds. The unit mentioned above will have a humidity reading to help with this.
As far as the difference of keeping Boa and Python, I'll let someone who actually does this speak up. I haven't had pythons for years, so rather than ill advise, I'll chime out.
Good looking snake. I hope it turns out to be a nice pet for you.
Rick