How many different kinds are available, (models, colors, etc... other than the newer white one) and how many of them are interchangeable with other models?

Like... will this remote:


...for a 6230CD...

control a 6400? I noticed that both of my 6400s have IR sensors, but neither came with remotes... what can they control other than the TV tuner? Can I change audio playback or play/pause/skip a CD track with it?