1. Talking tibar - a nasty character not really worth helping - should be a bit south and slightly east of where you start at the first teleporter (I'm going by memory - you can check the maps for exact location).
2. If one of the town females gives you the quest to steal a book from the Renaar, talking to the librarian gives you the quest to purify the lava. If not, you never get it.
3. The stone is put in the broken teleporter north of where you got it - in the area where you should be constantly and annoyingly teleported around until you get close enough to the broken teleporter to slap the stone in.
