"acquired powers" are powers like raising the dead, things you learn. I think "animate corpse" is the only one right now. Breathing fire and whatnot falls under the "natural powers" section if the creature has it.
Thanks for the clear up. Are acquired powers addable by mods or hard-coded? I'd love to add something like a basic Magic Missile or the power-holler from Skyrim, or maybe a Super Mario Brothers-esque fireball.
EDIT: Spells seem to be based on adding or removing tags from a targeted entity, based on the raws. Maybe a mayhem-causing spell that makes a targeted person act like a rabid animal? (imagine turning a person in the middle of a bazaar into a rabid beserker. hilarity)
EDIT2: I might as well make a playable race with inherent magical powers once I get the hang of how powers work. Maybe a "brainflayer", a pink tentacled biped with a host of magic powers depending on the caste. Imagine getting seiged by them...