My radio is a special case. It's a old VEX robotics radio ($25 new), which uses 75 MHz, but I've upgraded it to 2.4 GHz using a Corona DIY conversion kit (another $30).
The XBee onboard my quadcopter is only there to make wireless configuration extremely easy, the GUI can display my sensor values and I can adjust many flight characteristic parameters wirelessly.
If you are looking for a good radio for control, I'd look towards the $60 Turnigy 9x, the main appeal is that its firmware is hackable
Motion sensitive controls will be cool but I don't know how well it'd work in practice
I wouldn't recommend this project to a newcomer either, you are right about the safety issues too. I've done other stuff like spudguns and go karts and plenty of electronics, not much scares me. A good starting point for a newcomer would probably be a upside-down pendulum type robot aka self balancing robot, which involves a lot of the same control theory and sensors.