Well I have experience with the futaba skysport and yes its a great 4 channel transmitter. On some bigger planes 4 channels could be a limited factors but, for all trainers, which i hope your flying, couldn't be better. Check with your local club and see what brands everyone is using. To be buddy boxed with an intructor they have to have the same radio.
All servos will work with any kind of Reciever. Some of the older airtronic servos had there wiring reversed but, that has changed with their servos now. Futaba servos has this notch on one of the ends of the connector which interfers with some extentions / recievers but, most people cut the notches out.
As for recievers with transmitters they are different. Futaba transmitters wont work with JR recievers etc but airtronics i dont know. Can someone chime in for me for that one. Some companys like BERG or FMA direct make recievers that will work with any transmitters since they can sense what the transmitter is using.