Hello. I'm facing the same issue, including point 3. I'm unable to add our companies repository and therefore cannot evaluate ReviewBoard.
I'm trying to enter a SSH-based clone URL under "Path", and after clicking "save" I am prompted to trust the servers fingerprint. If I do that the page reloads with an empty form.
The server's fingerprint is already trusted for the www-data user, as per /var/www/.ssh/known_hosts, connecting via ssh on the console (as www-data user) does not prompt for fingerprint approval.