What do you think about that: All tracks are added to a list, and the list gets shuffled itself. Playing starts from beginning. When adding more tracks, they will be appened to the end, and the list gets shuffled again. Playing starts from beginning again.
When switching from and to continuous mode the current title could be searched, and playing continues from that position.
Maybe cover art could be saved binary in the DB, but I don't know exactly, if this will work (well).
On the other side: Doesn't MAFW provide a shuffle mode with a given playlist?