I might be wrong about the front light part, since I am still an observer of limited information.
However, I still dont think that light cover it is powered by the reader: check out the photos leaked out over a month ago:
you can see that the upper part of the reader on the back is pretty much sealed up, no ports or anything, there is no way to draw power out of there.
So, this light case too me, seems runs on zero batteries. I dont think sony will go non AAA batteries just because they want to place smaller batteries on the back, and that kind battery will be a pain to replace over and over, I dont sony will ever make that kind of decision.
Here, I stand by my original purposal: this light case is a smoke.