Do these mount using the factory bolt holes?

Yes. The over fenders attach to the existing fender mounting points without drilling or welding. Your vehicle's stock fastener locations will align perfectly with the assembly.

What surface prep is needed before paint?

Sand the surface with medium-grit sandpaper to scuff the finish, then wipe clean of dust. This ensures your paint or clear coat adheres properly. No additional primer layer is required before top-coat application.

Will the wider fenders interfere with the wheel well or suspension?

The 40mm extension is designed to clear factory suspension geometry and wheel fitment. Before installation, verify your wheel offset and sidewall height against the new body width to confirm tire clearance in full compression and at full lock.