Hi,
So I read all the Help posts I can, and am generally loving the ccmixter idea and ethos… but still can’t work something out.

Can I post up my own original song AND the associated audio files, or can I only upload the individual stems? Would seem to make sense to me to have people hear the full, original track, and also provide the stems for remixing… or am I missing something?

While you can post your original track as a sample (but not as a remix) and include the stems, when posting samples, the general consensus is stems or sample packs with a preview mp3 are the best way to have your samples picked up and remixed. You could just upload the stems and include a link to the fully mixed song as a reference. If there is a vocal part, you can uploaded that separately as an unaccompanied acapella.