Tim,
Sorry for the delayed response. JFBConnect does have support for jReviews for Open Graph tags. We don't support automatically adding social sharing buttons to jReviews though. You can add those buttons using the JFBCSocialShare module or various other features.
As to your specific questions:
1) No, we don't do this automatically. You can configure the JFBCSocialShare module to show on your jReviews items in a specific module position or floating like at the bottom of this site. You can also modify the jReviews templates to add our EasyTags, like {JFBCFacebookLike} wherever you want the Like button to show.
2) Yes. Our Open Graph - JReviews plugin can automatically try to set title, description and images for jReviews content. You can also set these tags manually on each jReviews listing by adding custom tags, like:
{SCOpenGraph title=Title for listing}3) Yes, the user must be logged in using Facebook to have an Open Graph Action trigger on their behalf. However, I wouldn't focus just on Open Graph Actions. Limiting the ways users can register can ultimately limit the amount of user's that register. Consider Open Graph Actions as a bonus, if it happens, but first and foremost, getting user's into your site is (usually) more important.
Open Graph Actions also get relatively lower weight than some other content postings to a user's Feed. While beneficial, it's not guaranteed to show up in the user's feed that a friend sees whereas a post that user makes intentionally obviously gets higher weight.
I hope that helps answer your questions, but if you need anything else, just let me know.
Thanks,
Alex
JReviews?
