There really is not much you can really check with a quick test drive, other than obvious defects. Find out what is the best method to contact anyone at the Reps business (via phone, fax or e-mail).
Get to know everyone in that company and what they do ... and can do for you if you have a problem.
Look over the paint to see if any chips or marks anywhere. Did you have them install the 3 M protector film? If not, why not?
Watch out for the pedal spacing ... it is very close. You
WILL step on the brake a few times when you are trying to depress the clutch ... therefore, make sure you put on the 4 point harness, rather than just the lap belt.
Get an Owners Manual and read it 3 or 4 times when you get home.
Be extremely careful when putting the license plate on the car. Make sure you use very short bolts ... you do not want to scratch the paint, do you?
Congrats on your wise purchase ... and have fun. I know I do.