I wouldn’t worry about brushless upgrades now, just buy the kits, build and enjoy for the time being. If you are going to upgrade anything, the first thing would be proper bearings instead of the plastic bushes the kits normally get.
As for building, if you’re inexperienced I would say do at least one of them before and have it ready to use on Christmas day.
I always used stick controllers, never got on with steering wheels, but there’s not really any advantages, it’s just whatever you’re used to. You’ll have just as much fun either way. Maybe a youngster might find a steering wheel and trigger a little easier to get the hang of? Not sure, just speculating there!
EDIT: Toppers beat me to the punch there on pretty much everything I said!