Regarding the spells... unless you have some immediate inspiration for imperial counterpieces to the above-mentioned spells, I would be going to add these lines to our npc scripts now. Calling removeSpell on an npc that doesn't have the spell has no impact, I have tested, so we can just batch remove them in one go (and do the same with the shotn-npcs while I'm at it).
Edit: Btw. you seem to be right about auto-adding of spells to npcs, i just set up a sorcerer at level 20 and voila, he had ghostcurse and pc_ghostcurse in his spell list. So it's not limited to our own spells. I'm going to edit our custom creature spells so they don't get assigned to npcs anymore.;remove dunmer spells from cyrodiil npcs
removeSpell, "almalexia's grace"
removeSpell, "almsivi intervention"
removeSpell, "Cure Blight_Self"
removeSpell, "Cure Blight Disease"
removeSpell, "ondusi's open door"
removeSpell, "ordeal of st. olms"
removeSpell, "rest of st. merris"
removeSpell, "rilm's cure"
removeSpell, "rilm's gift"
removeSpell, "seryn's blessing"
removeSpell, "seryn's gift"
removeSpell, "shield of the armiger"
removeSpell, "sotha's grace"
removeSpell, "sotha's mirror"
removeSpell, "summon ancestral ghost"
removeSpell, "summon bonelord"
removeSpell, "summon greater bonewalker"
removeSpell, "summon least bonewalker"
removeSpell, "ulms juicedaw's feather"
removeSpell, "veloth's benison"
removeSpell, "veloth's grace"
removeSpell, "veloth's gift"
removeSpell, "vivec's feast"
removeSpell, "vivec's kiss"
removeSpell, "vivec's mercy"
removeSpell, "vivec's tears"
removeSpell, "vivec's_wrath"