(1) It's called Mixing in the Spine runtimes and it's possible. Not sure how to do it in cocos2d. But keep an eye out for those methods that mention "Mix".
(2) I think what you're trying to do is move the pivot, which isn't possible yet. The root bone is just like any other bone: If you move it, all its children move with it.
(2.1) Moving the root bone to move your sprite isn't recommended. But that's something entirely different. Just a heads up.
