2) I just realised there's a bug where these methods aren't minified correctly. It should be fixed in the next release (after r118).
3) Every animation frame has its own origin, and the object itself separately has an origin. Sprites copy the animation frame origin to the object origin. It sounds like we need to make sure this happens when calling the SDK methods.
4) I'm not really clear what you're trying to do? The SDK currently does not support removing animation frames, but why do you need to do that? Shouldn't you just add the correct sequence of frames?