I believe rebuild database just deletes the database file from the iPod and creates a new one based on the MM library, matching it to the tracks on the iPod. I don't think it deletes any music files.

Yes, to back up the database all you have to do is occasionally copy MM.DB to another folder somewhere (I have linked to the default MM.DB file location in my sig). Alternatively, you could have MM back up your database and other important MM system files automatically by installing Trixmoto's [url=http://www.mediamonkey.com/forum/viewtopic.php?t=7746&highlight=backup]Backup script[/url].

I don't believe there is any way to force ratings/last played if it fails, though I can't imagine why it wouldn't work.

If I choose to rebuild the database on my iPod, what does that do? Does it delete everything off the iPod and then resync? If so, I gather that the point is to make the iPod database match the MM database.

As far as the MM database goes, I have seen on the forum that it is a good idea to back it up occasionaly. To back it up, do you just locate the file and copy it to a folder?

Finally, occasionaly my ratings and 'last played' won't sync from my iPod to MM. Is there a way to force an iPod to MM sync on songs that have this issue?