I've read a bunch of informative topics on Smart Plalists, but I'm still confused on a few points.

I'll state my primary desire simply, and then delve into some of the points I find confusing: I want iTunes library to be updated by the iPod's metadata, and vice versa. If I play a song 6 times when listening to it in iTunes, I want the iPod to add those six times to the four times I had already listened to it before my last synch. If I rate a song while listening to it on the iPod, I want the rating to transfer over to iTunes the next time I perform an update. Is this possible?

In general, I like to manually update my iPod (I have some stuff on my iPod that is NOT in my library, and I don't want to lose it). Reading some fo the forum topics, I am led to believe that if I tell iTunes to only synch certain playlists, it'll erase anything on the iPod that is NOT part of those playlists. Is this true?

I've read recommendations that I can create a playlist that has my WHOLE library, and therefor, I lose nothing... except for the stuff that's on my iPod that's NOT in my iTunes Library?

If I update a song on my iPod that's in a smart playlist that I've chosen to synch, will the updates to that song be transferred from the iPod to iTunes?

What happens if I play a song three times in iTunes, and listen to the same son 2 times on the iPod and then synch? What happens if I have a song rated as three stars in iTunes, but 5 stars on the iPod, and then synch? (What would make sense is to take the rating from whichever device played the song last)

I've read discussions where folks will create a smart playlist that plays, say, songs not played in the last week, randomized to 100 songs. If these smart playlists are synched, I infer that iTunes selects the 100 random songs that fit the criteria and then transfers them to the iPod. As one listens to that playlist on the iPod, the meta data is changed, and they disappear off the list (but are still available for play through browsing on the iPod). The next time the iPod is synched, the iPod transfers new metadata regarding the played songs so as to remove them from the smart playlist in iTunes, the songs from the previous synch are removed from the iPod, and then iTunes transfers a new hundred songs fitting the smartlist criteria to the iPod. Are my inferences correct?

These are all mysteries to me, and I don't have the time and patience required to test any of my suppositions (especially since there's content on my iPod, but not in my iTunes music library...I'd hate to lose it). I have a "synching" feeling that what I'm looking to accomplish might not be possible at all. Does someone know the vagaries of smart playlist synching such as to posit an answer to my inquiries??