You can map network drives as ftp, just need to use the
ftp://servername. As far as keeping up with your music that may be questionable. It will all depend on how many users and traffic it generates.
V4 on units with 64meg works fine. You can turn off services you do not need. Just go through the networking screens and un-check anything you are not using.
If I recall the factory had a way to backup any OS, but sadly this was not released to the public. Most units were not design for users to service them.