Will this wing use the factory mounting holes?

Yes. This spoiler is designed to align with existing A Spec mounting points. Verify hole locations on your vehicle before drilling any new fastener holes.

Does this panel add significant overhang to the trunk lid?

The A Spec profile maintains factory proportions. Check your existing trunk clearance (especially if you have a rear bumper modification or trailer hitch) to confirm the wing will not interfere with your setup.

What do I need to do before painting?

Sand the panel to an even texture, fill any minor voids with filler if needed, and apply a quality primer coat before your final paint. Start with a coarse grit and work to a finer surface before priming.