You'll probably want to check with the race directors at the local tracks and see what the club rules are too, just to make sure that you're meeting the requirements of whatever class you want to race in, with your purchases. I made the mistake of going out and buying a 17.5 brushless motor/esc combo because it was considered stock by ROAR and later found out that brushless was still only allowed in mod classes at the local club races. Had to go buy 27t motors to use, instead.
For sure agree on the spread spectrum radio...that's a must have, now.