1. By syncing with iTunes, same as always.
2. Yes
3. Yes and it depends.
A. If you each log in to your own individual user accounts and you each have your own individual iTunes accounts - Yes.
B. You keep 2 individual iTunes libraries under the same user account - Yes. You can create a new iTunes library by holding down the option key when you launch iTunes. Then do the same each time you launch it to select which library you want to load.
C. No, and the one I recommend. My wife and I both sync to the same iTunes library and have only a single iTunes account which we both use. This way we both have access to any music, movie, TV shows, books, or apps that either one of us purchase. Never catch us both purchasing the same thing. This is a big part of syncing, choosing what you do and don't want out of your entire combined library.
