RE: Are radios interchangable?
The same goes for the rest of the flight pack (Batteries, Switch, Servos) For those on a limited budget, it's very common to switch equipment from one plane to another.
Of course, there are limitations to this. The servos that came with a 4-channel Trainer will not be powerful enough to fly a BIG aerobatic plane.
But yes, for the most part, it's perfectly ok to swap your radio around