Are NPC humans, elves, etc. always Might 2, or can notable ‘boss’ NPCs be Might 3? Is there a circumstance where they should be Might 4 or higher?
Should NPC evil wizards and chaos cultists use spells out of the book, or should they just be statted up as weapons for use in conflict modes?
Excellent question.
Normal folks like millers or soldiers should be Might 2. NPCs that are adventurers–warriors, magicians, rangers, burglars, etc.–should be Might 3. If they have access to a spell, prayer or potion, they can use that to get a higher Might. You are, of course, free to increase Might as you see fit if it makes sense: they’ve just completed some crazy blood magic ritual, for instance.
I give NPC magicians and cultists spells and prayers out of the book. But I can totally see a case for just giving them spells as weapons in the conflict modes. It really just comes down to what you’re comfortable with as the GM.