OK, this may sound stupid, but how in the world do you keep going down in the mines? I freed the prisoners, killed everything I can find, but can't find any steps down further into the mines. Where on earth are the stairs after you free the prisoners? Help!!

Have you met & freed the dwarven NPC from the cells? Do that, he will join if you want. Then go out of the cells - minor battle with guards, and go down stairs on SW corner. Small room, traps in corridor then some tougher guards and the mine boss (forget his name). Get the key from his dead body to flood the mine. Check all his chests and the other guy in the side room. Kill the slime then take the elevator back to the first level. Use the key to flood the mines - cut scene - then you're out.