The G35 coupe with manual is more expensive because it's meant to be sportier with bigger wheels and sport-tuned suspension (I think).

The GSR is a 5spd manual with the reverse after 5th gear.

Finally, you should have asked these questions before you bought the car. I have no regrets driving the stick Civic I had in high school. You quickly develop coordination and strength in your left leg when driving in traffic in Dallas TX when you have to clutch in every couple of seconds. I have only have regrets going to auto when I got my teg in Houston TX. It's much more fun and engaging to drive a stick. Only advantage with auto is if your left leg is feeling lazy.