Update:

Fluid in the back of the tank was low, slightly below the level of the nipple where the clutch fluid hose connects. No joy on the clutch working after I topped it up -- feels like there's air in the system. At least this appears to be a hydraulic problem, not an issue with the clutch itself.

I moved it (clutchlessly!) to a parking spot across the street, which buys me a day to deal with it. I'll try to bleed it tomorrow.

A few questions:
(1) What size (inside diameter) Tygon hose should I grab to cross-connect the brake bleeder to the clutch slave nipple?
(2) Are all of the bleeder nipples 7mm (brake, clutch master, clutch slave) or do I need some other size of wrench as well?
(3) Should I use a one-way speed bleeding valve on the clutch master nipple?
(4) Any gotch'yas in removing the under-dash panel to get to the master cylinder?

Thanks!