does the new itunes require the libray to be synced?
I'm afraid I do not understand this question.
I can say this: You put songs in your library. Your library may then be synced to an iPod. If you auto sync your iPod and you delete songs from your library, when you sync again, the songs will not be on the iPod. You can avoid this by manually managing your iPod.
Don't know if this helps, but, again, I do not understand your question.