Hi. Welcome to the sport and to the forum!

Your development from your BMX years will still be there and likely expedite progress.

Basic fitness goes a long way. Weightlifting and interval training will definitely work to jump start any new racer. No need to get a super custom program.

Most beginner and intermediate races last from 30 seconds to 15 minutes. Any self-made program that does work on both of those ends will have you in a great place.