Is there a way to revert back to the default for a character after you have edited it? I got the stats back, but the image is still the new one. I want to get the old one back.

Is it an original card you´ve edited? In this case you have to do a complete rollback by clicking on "Restore All". After this is done and you want to alter it again, just save the card somewhere in a folder so you can load it again in case to get the stats back. If it was a custom card, just download it again from the downloads-section.

I accidentally altered the original Ackbar card with a custom card from the card database here. The stats went back, but I can't get the old Ackbar picture back.

Than do that what I´ve mentioned above. Put in your CD, switch on the RebEd and restore all settings again.