Originally Posted by
Spoon
Many of your questions, only yourself can answer because it is your own music collection. You should not delete anything until you are certain where the duplicates are from. In the de-dup program, click the spanner icon top right and see which location is being index, it should be only 1 location, no your nas drive. The 'i' info button in dedup will show where the files are located for a detected duplicate.
About album art, you can run it manually, that is for each album you click the 'fix' button next to the album, to just do that album.