RE: Good 2nd remote for the price
Yes, if you get a transmitter (tech. term for what you want) on the same frequency as your current plane, you'll be able to control it. And you can get a transmitter on any channel you'd like, as long as it's for an airplane. (Channels are classified as ground or aircraft, can't run one on the other)
I know JR has a brand new 6 channel computer radio, all the gizmo's you'll be able to handle for a while, but I don't know the price off the top of my head. But I'll guess it's going to be under $300, well under. Futaba's basic 6 channel radio is under $300 too, but it dosen't look to have quite as many features as the JR does. HiTech makes a nice 6 channel, as does Airtronics, but if you're going to use JR stuff I'd stick with a JR transmitter. They're all good.
As far as digital servos, I wouldn't bother right now. When you need them you'll know it.
Surf the manufacturer's sites for radios, most of them (at least Futaba and Airtronics that I know if) have the manuals online. Although it's not the same as having the transmiter right in front of you, reading the manual can give you a good idea of the radio's capabilities, and how easy it is going to be to program it.
Andy