It does Ajax. Rsr2Png handles Alpha Channel. Doing the whole library at once has already been asked. I'll do it for sure but I don't know when. At the moment Rsr2Png rely on its own seeking algorithm. When I'll imrpove it it'll use the P3dO scan view. Then if you scan all subfolders from a root folder you'll have what you ask - automatically. Delete Png after conversion, same anwser. I know I have to hurry. Once P5 comes out Rsr2Png must have all these features.

Yarp - author of P3DO Organizer for Poser