Well if you look in your local library and look up snakes on one of the terminals you should be able to find plenty of information about breeding king snakes. Breeding is time and money and you have to realize that you could have anywhere from 5 to 20 eggs to hatch. Once they hatch you'll have to take care of the snakes. Which includes getting them to eat for the first time,heating,water,cleaning the enviorment they are in. Don't just rush into it. I know you think snakes are cool and it would be very cool to breed them but please make sure you know exactly what you are getting into before hand.
As far as people buying snakes from younger teens the pet store around me get a LOT of there snakes from a local breeder who started when she was 14 y.o! The pet store also breed there own snakes of course but she supplies them with a lot of cali kings,tangerine honduran milks and various other milks. She is 18 now and going to college so she gave up a lot of her snakes to the pet store. This pet store has been in the news for a lot of the exotic animals they have at the store. So yes people will buy from a 14 y.o as long as the snakes are healthy. I wouldn't have a problem with it at all.