Thanks for testing! Could you please send me the database file in /home/user/.config/Katastrophos Labs/quasar/quasar.sqlite3 to quasarmx@katastrophos.net (big files are okay). This file should help shed a light on why you have duplicates in your playlist.
QuasarMX is very conservative in requesting new connections as I personally find it really annoying when applications constantly ask for internet connections (e.g. Nokia's Mail App)
Should work out of the box. It looks for image files in the same directory that the music file is in.