1. You get the Amulet of Knowledge when you defeat the Stone Titan boss. (Attack the hole in the desert on the world map.)
2. The balloon can land on Mt. Horus to pick up the fiancee. I wonder if you have to exhaust your other options first though. Have you had the conversation where the party realizes they'll never get her to follow them off the mountain? (And the staring contest with Hans...) And you have already defeated the Succubus, right?
3. The Magic Pot artifact can be used as a cooking pot for the quest in Tropicalia. But you need to have Evelyn (the cow) in your party.
And a question of my own. I'm getting ready to play a second time, with the goal of 100% completion. Does anyone know if the bugs where quests and relics are miscounted have been fixed?