SBC,
Welcome to the Colorado karting community!
Your question has been asked before many times. So instead of repeating everything, why not go to e-karting news website, get on the forum for “General Discussion” and do a search for:
new to karting
which class
which chassis
which engine package
etc, etc,
For Colorado-go to the tracks and talk to the owners, go to races and talk to the racers-everybody is helpfully and will answer all and every question. Next raceGrand Junction Sept 16-18, IMI Sept 25, Bandi Oct 2.