I know that the willpower (head) stat is for questing investigating , the fist and foot are for fighting and evading, but what about the wisdom stat? What's that do?

Your information is wrong. You investigate with lore attribute. Willpower is used to withstand an unspeakable horrors that game throws at you.

You also use Willpower to cast spells (at least, in the Mystic cards we've seen so far).

Okay, cool.

Book symbol is intellect in the card game, rather than lore.

I assume that the name being different from what's been used in the board game is deliberate, to represent deductive ability rather than knowledge of arcane spells and such.