Yes, Auto Tweet is good if you want the new articles to automatically post to your social pages. JFBConnect doesn't do that, and we generally recommend you don't automatically do that. It takes a little more time to post manually, but you can post a customized message, post at the right time for your audience, and in general, you can't accidentally duplicate posts or post before the content is ready. That's our opinion though. Automated tools can work just fine.
As for setup of the Facebook Open Graph actions we support, you should read the full
Joomla Open Graph
configuration guide. That will hopefully explain how to setup some of the actions on your Joomla site.
In general though, you'll want to install any of those opengraph plugins for extensions you have installed, like Content (Joomla Articles), JomSocial, EasyBlog, etc. Then, Open Graph description tags will be automatically added to pages for those extensions. If you want to setup the automatic postings when user's interact with your content, the guide above should help explain how to do all that.
Hope that helps get yous tarted,
Alex