You should contact your local Officer Recruiter, make sure it is the Officer Recruiter.
The main screening classes are Calc I & II, and Calc-based Physics I & II. Your age is not an issue at all, as the cap is 29 for the NUPOC Program (there are waivers for this, N/A in your case). Which part of the program are you looking at? Your GPA is a little low for Naval Reactors Egineer, but good to go for the other three - Submarine Officer, Surface Wareface Officer (Nuke) (no self-respecting man would want this though, you can do all those missions from under the water as a Subamriner), and Nuclear Power School Instructor.
There is no OAR test for this program, you apply and then you get screened and invited to interview or not invited.
If you have other questions specific to the NUPOC Program you can check out the blog maintined by one of the other Nuclear Program Officers,
www.navynupoc.blogspot.com