1. You need to remove the install directory as the error tells you to do and our upgrade and installation instructions state the same.
2. If you follow the instructions at the bottom of the upgrade and install directions on the plugins making sure all 3 xml files are 777 permissions and then generate your plugin xml which you install into vb
you should get no errors.
3. Please reference my answer above. The plugins do work if installed correctly. I would need to see your actual install to comment further. A community photo gallery - ReefTalk Gallery
4. Not if they are true admins. You can have moderators but true administrators usergroup 6 have full admin permissions in the program.