Don't think we have any specific plans for r500. The reported power management issues seem to be largely on newer hardware so far.
We are working on improvements to power management but hard to give ETAs because it depends on what info we end up being able to release and when.
No specific plans for 2D acceleration AFAIK but periodically new DEs and apps use the accel in new ways and bottlenecks occur, and in those cases we usually try to pitch in and help speed up whatever has become a problem. Are you talking specifically about r3xx-5xx (which has dedicated 2D acceleration hardware) or r6xx and higher (which does not, and therefore uses the 3D engine for everything) ?
Video decoding has been discussed at length in the last week or so -- Christian has been working on it or a while, but that work is speculative in the sense that we don't know if we will be able to release it. The day we know for sure, you will know as well.