If Kalanyr starts lecturing on the secrets of 10th level magic, then I, my Gem Dragon allies, and my Draconic Planar allies teleport into the back of the crowd and take notes. We are, after all, Dragons.
Kas is indeed a vampire: the first sentence describing the Sword of Kas in the DMG is "The vampire Kas was the dreaded lieutenant of Vecna..."
edit: As for the helms of opposite alignment, they're only 4000 gp a pop, but they're one shot items. Useful for enemy commanders and charismatic leaders, but not for masses.