No, you can buy just the Digi Propo controllers by themselves if you want...The regular Propo can be found for super cheap at
HLJ or you can get the better model, called the Digi Propo Special but those will run you $45US+...If you're going to opt for the better remote, you might consider getting a DigiQ to play with too...They're a good amount of fun.
It's FULLY proportional throttle, none of those low/medium/high speed adjustment...The more you pull the trigger, the faster it goes.
IR has a general LOS (line of sight) range of about 20feet...Limitations are that you have to be point the controller in the general direction of the car, and people have reported bad reception in bright light (like sunny day, outside) situations.
It's a definite risk, something to serious think about before trying.