If you just want to set one image to be used on every page for wall posts, what you stated above is correct.. Just the image=xxxx tag in that box. Once you enable Open Graph integration in JFBConnect, if you don't set a default title & description (in that box) and don't use the {JFBCGraph title=xx} tags on the page, then we'll automatically set the Open Graph title & description tags to whatever the standard meta title & description tags are. So you shouldn't have to worry about that either.
If your meta description tag is already being translated (by JoomFish) then you should be all set.
Finally, note that when you setup Open Graph tags, it can take Facebook up to 48 hours to 'see' any changes you make to them. You can always use the URL Debug tool of theirs to instantly see how your pages will be scraped by Facebook though:
developers.facebook.com/tools/debug
Hope that helps, but if you have other questions, just let us know,
Alex
Unclear about Opengraph
