If you don't have a scale,all you have to do is feed him prey that is as big as the fatest part of his body,a little bigger is fine,like enough where u will SEe a bulge in his belly..
as for the bad shed,you got to keep the humidity up..I don't know what kind of set up you have but whatever it is ,it's wrong. Soak your snake in warm water for like20 minutes,then get a damp rag and run him through it,tht should help take the extra shed off....this is what I have read around here. My snake once had about an inch on his tail,did what I read and worked perfectly.
Also if your snake is out and about a lot and not hiding just about all the time,most likely something's up..what kind of investigating and readi did u do before you got your snake? Did you just go blind into it? It's animal and requires work,daily maintanence..u just don't drop it in a tank ith heat and your good to go