Q: 1. What's the difference between valueParm and targetGeom?

A: A valueParm (FBM) channel is a control channel, its only function is to output a value that can be read as input by other channels, is not a morph in the usual since as it does not contain any deltas. The targetGeom channels are morph channels the do (usually) contain deltas, the deltas are the actual morph. A targetGeom channel can be slaved to a valueParm with slaving code so that the channel gets an input from another channel, this is known as ERC. A number of targetGeom channels in different actors may all be slaved to one valueParm channel in the BODY actor. Collectively that is known as an FBM (Full Body Morph). So valueParm are control channels, and targetGeom are morph channels.

Q: 2. What's up with the PBMCC_50 stuff?

A: I'm not sure exactly what you want to know about it. The PBMCC channels are blank (no deltas) channels that third party morphs can be injected into. PBMCC stands for Partial Body Morph Community Channel.

I'll have to think for a few minutes about how I might be able to answer your third question.