The bake scale option transfers transform.scale (using the unity transform widget) to sprite.scale, and sets transform.scale to this 1,1,1. This lets you conveniently use the built in scale widget, and click bake scale once at the end to get dynamic batching working again.
The Api stuff should be done this weekend. There isn't a list, we're simply documenting the relevant ones using XML comments, and creating doxygen docs.
The docs for the new features will probably take a while longer, screenshots always take ages to do.