What popup messages do you mean? If it's the Login dialog or Like comment areas, those should be translated by Facebook automatically. We load their library using the same language that your Joomla installation is using.
If you mean things, like the "You are now being logged in" text, that can be found in the /languages/en_GB/en_GB.com_jfbconnect.ini file. You can copy that to your own language directory, if yours is one that isn't included with JFBConnect. Once there, edit for your own language.
Finally, for the Google description, we haven't heard of that problem before. We do include that text at the top of the page though, so I can see how it's being used. We'll definitely move it to the bottom of the page in the next release so it's not as prominent. Until then, we'd recommend ensuring that your site has good meta title and descriptions, which Google should pick up on. Alternatively, if you disable the Automatically Login Facebook Users setting, we won't include that text in the page. Once we come out with the next release, with that text at the bottom, you can re-enable it.
Hope that helps!
Alex
How Do I Translate language on all jfbc pop up messages/windows?
