Okay, all these errors with the drag and drop version I cannot do anything about, really, at the moment. Perhaps BobbyQ can give a hint or two.
For me it's not a problem that the thing would browse my miniplayer. The original album art is on your PC right? And having only some converted would look strange to me.
All I know is that my 'do them all' version works perfectly fine, also with a provided background. Just remember to call the meizu_albumart.bat file (after connecting your miniplayer and changing the paths to the correct locations) and not the other one. This is tested on XP only, though. I have no idea how Vista works with this kind of stuff. I'm not touching Vista. Hurts me enough to use XP.
And of course it's no problem to integrate this thing in BatMan. The more people can benefit, the better it is.