Hi
Are you sure it's good to begin endurance with a 9hours race?
When I see your friend's stats in LFS World I see that he has only 227km and only know the XFG-Blackwood combo... Maybe you should start with something easyer? But well as long as you are both clean, respectful and read the rules there is no problem, just an advice
Anyway I'm going to answer your questions
1) Just look at the picture in first post: It's Aston GT (Gran Touring)
2) One of the drivers must be in car and the other one spectating. Both have to press N in your keyboard enough times so the driver list appears. Then you or your co-drivers must press "T" in the drivers list near your team mate's name. When you do that you request a driver swap. Then the driver that is in car must pit and when the pit stop is finished (adding fuel, repairs, etc...) you stay in the pit and the other driver (that didn't press T) must press T too and here you are
3) A request of what? If you mean suscription it's done when I see them
PS: Oh and sorry for my poor English... I just hope it's understable