some of the best advice i can give is to get your tank set up long before you actually get your snake. Glass tanks can be hard to maintain the heat and humidity (as i found out with my first BP Jake). Make sure that you get some kind of belly heat for them and ALWAYS put it on a good reliable thermostat. This is one of those cases where you usually get what you pay for. I like the herpstat, but theres also a decent one on amazon you could use if you're just doing the one small tank. Set your tank up like a week in advance and see what all it takes to maintain the proper heat and humidity that your snake needs. That way when you actually get your new buddy, you aren't learning on the fly, and potentially harming him/her.
As for feeding, I like to feed live or fresh killed (just a preference), but i also like to stick to rats over mice. Hatchlings can usually eat something around the size of a hopper mouse. The 10-15% rule I also think is a great idea for the first while in the snakes life. Gives you an idea of how heavy the food should be. Just keep in mind that the girth of the rat should be just slightly bigger than the larges area on your snake. Best of luck and I hope all goes well.