1) It could be that you have very little space left on root (on a 5500 for example), not sure about the relative memory (and ROM) size on a 5600.
2) Try using ipkg from the command line?
3) I don\'t think it tends to work on anything, try mplayer & xmms for a frontend.
4) Yes, OZ has later libs than the Sharp ROM. You may (will) have troubles with stuff directly from the 5600 Sharp ROM though as it uses that quicklaunch thing (I think the name\'s right). It\'s possible to get them working, but not worth the effort IMHO.
Si