What are the remnents of Hexpodean technology that are around? Or remnents of the hexapodeans themselves (as far as most people know, I accept in these cases there's ALWAYS some mysterious remnent hiding in a demiplane).

Were the Dragon Learners, according to records, loyal to the Dragon Lords themselves, or was it two factions who overthrew their masters together, and then fell to infighting?

You've mentioned that Underdark peeps are around, Drow, Duergar etc - where do they fit in, were there any Drow Dragon Teachers?