Ok, I know that there's supposed to be 10-20mm freeplay in the pedal, but is that freeplay the slack in the clutch cable, or from the throwout bearing at rest to contacting the pressure plate?

It's a little difficult to guage when it's freeplay and when it actually engages...

get some one to depress the pedal while you watch the clutch arm on the gear box

I always use my hand or a lever on the clutch arm and make sure I can hear
or feel the throw-out bearing touching the clutch as the clearance is felt.

There are many places where the PEDAL freeplay can be found other than this.

Cable stretch,
Too much bowden tube bend (it tries to straighten when the cable is in use)
Tunnel tube flex or loose in there.

Either way, you want some clearance between the throw-out bearing and the clutch.

On most late model diafragm clutches this clearance will reduce when the disc wears.