Confused On Social Stream

Your docs say to associate a Joomla user account with a Facebook user account to get Social Stream to work. I don't want to have to register anyone through Joomla, I just
want to use their FB or Twitter profiles.

The Channels feature is for posting to social channels that you own and operate, like a Facebook Page. It's not meant for all users to be able to post to or have to register using Facebook for.

You already have administrators on the site. If they are also the owners of the Facebook Page or Twitter Stream you want to post content too, they will need to associate their Joomla account to those social networks. Once that's done, you can hide the social login buttons from all other users so that they can't login that way.

Also, when I try to save my channel information, with my FB account details, it tells me I need an access token?

You need to authenticate with the user you've selected on the front-end of the site using Facebook. That's how Facebook provides the 'token' to JFBConnect which can then be used to post on that user's behalf.

I hope that helps explain,
Alex