Hey Adam, did you import the site from a different instance or version? Was a site deleted from this particular instance?
Regarding the no site issue, can you confirm when you did your backup it restored the data into the database you have defined in the connection string? That's always my first check, run some simple queries on the cms_site table as well as any custom tables or doc types you've created.
I've come across the "Information:Your UI profile is not granted with permission to access this section. Please contact the administrator." message when I've imported a 7.x site into an 8.x site. The problem is in v8 Kentico introduced an actual role the global admins have to be assigned to and the particular user you've logged in with isn't part of that new admin role. In fact, you can't even select it. What I did was exported the Global "CMS Global Administrator" role from a earlier instance of v8 and imported it into my trouble site and was able to get things linked back up and fixed.