Excellently thorough set of spoilers reference info. Thanks for compiling this. Couple-three additional points for the sake of OCD completeness:
If you talk to Dilbert *and then Sabrina* before you kill the chasm drake, Sabrina will reward you with an invulnerability potion and a return life scroll when you tell her it's dead. No change from Dilbert.
Cormac under Almaria has new dialog for you once you join the Scimitar. Could reasonably add him to the list of agents away from base. The quiet stranger in Fort Dranion disappears, though.
You can only get the luck bonus in Gremlin's Gold if you haven't killed Chuckles yet. If he's dead, there's no wall switch behind the level 3 barrier.