As for the Skull Cave fiasco, I fell victim to that. I found and explored Skull Cave before getting the quest about the Blackfang chest. Since I didn't have that quest, the chest wasn't triggered, so was not there in the cave. Later, when I did get the quest, the chest still wasn't there. Hence, I couldn't progress any further in the game.

Uh, maybe the Duncan you have to find is the imposter, since the Tomb-Duncan is apparently the real deal. I never finished the Tomb quest. My barb-barb-rune-druid party got to poor old Duncan before he shuffled off this mortal coil, so heard his dying words. It's saved, so maybe I'll go back and check it out.

The game version I have is v. 1.5-16336.