A general question

Yes, any number of iPods can work with a single computer/iTunes library. Each iPod's sync/manual settings are native to the iPod, not the computer or the library, so you could, for example, have a video iPod sync your entire library, while an iPod nano syncs only the "gf's music" playlist from the library, and a third iPod is on manual mode (or whatever setup you choose to use). I'd recommend sync-to-playlist for all iPods.