Is there a ride leader you can contact? Call them, ask them the questions that you are worried about. A 12 mile ride will probably not have a bunch of hammerheads on it so I think this would be a great start for you for a group ride even knowing nothing more than the fact that it is 12 miles.

Challenges are to be met head on. If you are worried about getting lost, get a map and ask the roads you will be riding on. You can do this!