This is such an open question.
Examples: You cannot combine iTunes Store accounts. You can do everything from completely merge content from multiple accounts to merely share media from multiple accounts in one or more libraries. You can each have a library and manage your own devices from each person's library. The libraries can be in separate computer accounts or one. Items can be shared by Home Sharing or Family Sharing. Separate libraries can each have their own media or you can share media between multiple libraries. To maintain different content you can either have one library syncing different playlists to each device or you can have multiple libraries syncing one to each device.
As you can see from the above it would help to have more limiting parameters to see which solutions work best for you.
I don't know about the iPod. Generally you can only transfer iTunes Store purchases from iOS devices to a computer. For other media you have to buy third party software because it is planned you are making regular backups of your computers.
iTunes: How to share music and video - http://support.apple.com/kb/HT2688 - about Music Sharing and Home Sharing