A healthy ball python can eat quite a bit - they have a tendency to get chubby. For some reason, my ball python was more sensitive to correct humidity levels than any other snake I had. When the humidity got too low, it would get 'flaky' skin issues and lose appetite.
+1 on the suggestion for a ceramic heating element.
You should never leave your snake alone with live prey. I personally never had a snake strike at me and I always fed in the snake's primary tank.
Good luck - snakes are awesome pets and are easy to care for. I'd get another one if my wife wasn't so creeped out by the idea.