Will this interfere with my trunk lid opening?

No. The wing mounts to the rear edge of the closed lid and clears when the lid raises. Verify your specific trunk hinge clearance before final tightening if you have aftermarket hinges or modified suspension that alters lid geometry.

Does this use the same mounting holes as the OEM trunk lid?

Yes. Factory mounting points mean you can use existing holes without modification. If your trunk lid has been repaired or replaced, compare the hole pattern to the wing before purchase to confirm alignment.

How should I prep the surface before painting?

Sand the surface and clean away dust. Refer to your chosen paint system's prep instructions for primer selection and application. FRP finishes best with proper surface preparation and a quality primer-to-color coat process.