Will this interfere with the trunk seal or bumper panel?

No. This lip mounts to the lower bumper fascia at factory-designated points and does not extend into the gap between the bumper and frame. Install it with the bumper fully seated on the vehicle.

Do I need to drill new holes, or does it use OEM mounting?

It uses factory mounting points. No drilling required. Verify your vehicle's OEM bracket configuration before assembly—some variations may require different fastener spacing. Your service manual will detail all mounting locations.

How do I prepare this for paint?

Sand the primer surface with appropriate grit to promote paint adhesion, then clean thoroughly to remove all dust. Follow your chosen paint system's prep guidelines—primer type and application vary by brand. A body shop can handle prep and spray if preferred.