Just replaced the clutch over the weekend. Definitely NOT a one man job, especially removing and reinstalling the transmission. It took me and my brother two 6 hour days to get it done. We did not have any power tools though. Some of the nuts and bolts were unbelievably tight, esp. the bolts on the U joint / drive line.
I found a little oil in the bottom of the bell housing. Clutch still had about .5 millimeters of surface left. I think the slippage was probably due at least in part to the oil in there, though I did nothing to fix that. It's very possible it was dripping off the fork, since there was no trace of it having dripped out of the transmission by way of the shaft.
All I can say is that I have a newfound respect for anyone who does this for a living, and hope I never have to do this again. Thanks for all the help, and I hope the new clutch lasts another 190k.