HUSBANDRY!
My bet goes to, the husbandry in the previous owner's place was off. Did they have a thermostat for the UTH?
Do YOU have a thermostat for the UTH?
That's what I say. Only time I've ever been bit by my ball was when I spooked it while cleaning it's vive, and I splashed it with vinegar water that was on my hand. We got past it. He bought me flowers.
As for the feeding, x2 what others have said. Ball pythons are FAT snakesthey aren't supposed to be lean. They are chunkers.
But, I will say that they can become obese. If it is an adult, you can feed every 10-14 days, based on what size rat you are feeding and the health of the snake.
I also suggest you check out the care sheet on the main forum! I say this to all new BP owners, just to brush up on info that may have been misunderstood or left out... or wrong. By no fault of your own.
All the best, and CONGRATS!