itunes and ipod sync

So i have my music library on my pbook and my ipod is auto synced to it. I bring my ipod to work and connect it to my PC and play the music through windows itunes. I have set the itunes to manual sync so it doesn't clear my music. I read that this will prevent my mac itunes from copying usage stats. How can I fix that?

Also, I'm making changes to the songs here on my PC, like changing names, metadata, or even deleting some songs. Is there a way to sync those changes to my itunes and my library?

Thanks in advance?

 

i guess the question was too obsure, so let me simplify this.

I guess if I want to take my ipod and play it on another computer through itunes I have to set the sync to manual. Thus when I go back to my main machine it'll be set to manual sync. How do I sync manually then? Do I just drag and drop to the itunes? If a file already exists on the ipod, will it overwrite it or just create another one? I had issues with duplicates so I'm just wondering.