Will this work with my OEM hood latch?

Yes. This hinge is built to factory geometry and works with the stock G35 latch mechanism without any adjustment or modification needed.

Do I need hood pins or bracing support?

Stock G35 hoods rely on the hinge and latch alone — hood pins are optional for show use or if you plan frequent removal, but not required for street driving.

Can I replace just the driver side, or do both hinges need to come off?

You can replace the driver side independently. If the passenger hinge is still solid, leave it alone. Remove the hood, unbolt the old hinge, bolt on the new one, and reinstall.