That tub size is going to be waaaaaaaaaaay too big for that young of a ball. I'd say go with a 28 quart or so or smaller yet. You want to be able to provide a thermal gradient (warm area and cool area) so you want enough space to be able to do that correctly. As for that type of heat mat, I'd steer clear of them. I had one for my corn on his tank before I switched to tubs/racks and they're basically junk. I had great luck with a Cobra T-Rex heat mat for a UTH after I got rid of the ZooMed but that's just me. Do what works for you.

Here's the caresheet for a ball python and it has a lot more in-depth info that what I could write out without forgetting something.

http://ball-pythons.net/forums/showt...s%29-Caresheet

If you elect to use a tub/Sterilite, make sure to solder holes in the sides of it or drill them out to allow ventilation and heat exchange in the tub. You'll also want some way of securing the lid as they can push themselves out and the latches on those tubs shouldn't be the only thing securing them. Lot to digest, I realize, so hang in there and keep asking questions! This is the place to learn and there are great people here to help, so good luck!