Most computer radios aren't just PPM or PCM, but rather they can be set to transmit either of them. All you've got to do is change a menu selection to switch between PPM and PCM.

Failsafe is a function of a PCM receiver, not of the transmitter. When the PCM receiver loses the signal from the transmitter it sends the servos into predetermined (provided the user sets them) positions. Used properly, it is not designed to try to save the model. It's intended to crash the model with the engine cut off, causing the least possible harm to people and property.

You can do two servos in the wing with a 4-channel, but you need to do one of two things: reverse one of the servos (changing it's normal rotation) or purchasing a "smart" y-harness that does the reversing for you. Anybody know of any other methods?