It sounds like you've got a lot of research to do still. Fortunately, I assure you the answers to every one of your questions are throughout various threads on this site.
How are you funding this whole operation? Are you going to have help selling off the babies? No offense, but I personally wouldn't buy a snake from at 15 year old. Do you have the money, space, and time to care for every one of the hatchlings if they don't sell? Ball pythons live for 25 years... have you thought about the future of your collection through the rest of your education and beyond? I know you're excited, but there is plenty of time for the breeding. What's important is that you've thought it through thoroughly enough and have support from your parents as well as the resources to properly care for the animals.
It sounds like you're well on your way. Good luck!