For what it's worth, I've discovered that apparently if you go to the iCloud.com website on your computer and login, you can create a calendar and share it with other iCloud members (you can't do this from your iPad or iPhone though, either via the Calendar app or the website). I'll have to get on that, as this will solve my own shared-calendar wish.
I
think that to share contacts (but keep some contacts separate), unless you share them individually, you can create another iCloud id and use it as the shared point for common contacts (add the new iCloud id under the settings for Mail/Contacts/Calendar). I have yet to try this, so unless you feel like experimenting feel free to ignore this until I mess up and destroy everything first, or you find better information.
Cheers,
Marc