noob MIDI/softsynth questions re: M Audio Key Rig

[L_Word77]

So I have practically given up trying to find any synth in the $500 or so range that has decent tones and features. Seems like the best thing I can do to satisfy my needs right now (ie: good piano, EP, hammond, synth) tones is to get a softsynth for my laptop and get a decent 88-key MIDI controller.

Right now, I'm thinking:

M Audio Key Rig 49 (the one with the "free" 49 key controller)
(plus the various freeware softsynths I already have)
M Audio Keystation Pro 88

However, I'm a bit of a noob when it comes to MIDI and softsynths, and I have a few questions:

1) The Key Rig website says you can configure different MIDI channels for each synth module (the piano module, the organ module, the synth module, etc.). Does this mean I could have one MIDI controller controlling just the organ, and another controller controlling the piano, for example? I also have an old 61 key Yamaha YPR-9 (learner keyboard) I've been thinking of using as a MIDI controller. However, it has no sliders/modwheel/etc. and has a broken E key right now.

2) Is the polyphony of a softsynth determined by the CPU speed of the computer? I can't seem to find polyphony info for many softsynths. I'm guessing it varies by whatever computer you're using.

3) How are the Wurlitzer and Rhodes sounds on Key Rig? I haven't been able to find audio samples of those online.
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