Not sure if you've had a chance to look at this yet - doubt it, considering all the other requests plus the various little bugs here and there - but I thought I would add another idea to this. If it were possible to tell MB to look for artwork other than folder.jpg by default (so albums will not look at folder.jpg but whatever you specify), this might avoid some of this annoyance with Windows resizing the folder.jpg files to 200px.
Also on a related note, when I use the "copy to same folder as the music file and name as" option, it seems to always want to output a PNG file instead of JPG.