1.
http://tracker.vbulletin.com/browse/VBV-1238
2. They are added/removed via Site Builder > Footer
3. Several bugs regarding sigs like this one -
http://tracker.vbulletin.com/browse/VBV-5829
4. Site Builder > Navigation Bar > click Edit pencil next to link > click Edit under Usergroups and set them up there.
5. Yes, it should have /core at the end
6. Links?
7. There is no default tab to upload to photobucket. You would need to create it.
8. I have no idea about that.