some of your questions i dont know the answer to, but the button hexagon controller is NOT proportional
the larger racewin, has a turbo/booster funtion, and some people have added a 3rd speed mod with an extra button on the top right of the controller...
there are tons of mods...but somewhat hard to get....
with the speed mods, you need to know how to solder, and the easiest mod to do, is have a 1 or 2 battery holder, and sodler them to the positive and negative points on the chassis where the +/- are..youll get about a 15-20% increase in speed..
if you want a faster motor, youll have to buy a new rear motor case, because the motors will not fit unless you do some cutting
fun stuff
no need to recharge it, there is a battery in the controller, and then batteries in the car itself...the car has an on/off switch, the controller does not