Well I have to say that I think that Wanda is definitely the predictamancer from Faq. Quite frankly we have no information on the mechanics to know if it is possible or impossible for a caster to change specialties. We do know that casters are extremely valuable units however and that they would most certainly be captured if possible. Combine that with the fact that only two specific casters have ever been mentioned as being in Faq, a predictamancer and a foolamancer and we know of only two casters that are from faq Wanda and Jack.

I also think this completely explains Wanda's inexplicable loyalty to Stanley. She didn't betray Faq, she screwed up. She failed (or at least feels that she failed) in her job of protecting Faq by stationing the foolamancer to prevent detection. She ended up working for Stanley (in a capacity that she enjoys much more) and because of all this she is desparate not to fail another leader. Guilt is a powerful motivator.

Also I think the picture of the predictamancer looks like Wanda.