Heh; you've picked the two-most-often-recommended books. I've read both. They're two very different styles of introducing poly concepts, so it's kind of a good idea to read both. Will be curious to hear which of the two you like best (if you have a favorite).
Are you still worried about the possible reactions your wife may have to another woman coming into your life? Is she strong in the communication area, or does she perhaps have a fear of conflict or confrontation or just doesn't want to hurt your feelings?
Do you want an NSA relationship? How do you feel about that?
Love means never having to say, "Put down that meat cleaver!"