No friends yet.
ArchIntercative's hybridauth works fine on 2.0 and provides integration with a bunch of OAuth 1/2 providers including Facebook and Google.
Have you saved the language file in the languages folder of the plugin you updated? If you change or add files in a plugin folder you need to backup them before replacing the folder with the new version. If you are using the translation editor plugin you might need to export the translations before upgrading a plugin. I don't know where the translation plugin saves the translations. But these translations are not plugin settings as such. The normal plugin settings are not lost when updating a plugin.
Can say more to images at the moment. Need to test.
Make a "site" plugin to store your site-specific changes, include language customizations. Try not to alter 3rd party plugins directly (or the core ones).