I usually use all 4 to hold the lever back during a red light, but once I've started to move again, I put my ring finger and pinky finger back on the clipon, and just use the other 2 fingers to upshift. I figured that was how most people do it.

Same here, even at the track.

I don't think I've used anything other than two fingers on each lever. I also keep those two fingers on each hand covering the levers at all times- they never go down to the clipons. I learned that way riding dirtbikes as a kid, and it just stuck.

I only clutch on downshifts?

Yeah I got that from a trackday instructor. You don't need to pull back the lever all the way anyway, so 2 fingers is enough to give it a nudge.