Will this interfere with my trunk seal or undercarriage?

No. Front lips mount to the lower bumper fascia and do not contact the trunk area. Your existing weatherstripping and undercarriage components remain clear of the lip profile.

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

It uses factory bumper mounting locations. Verify your bumper hole pattern before final fitment — if your holes align with the lip bracket design, installation is a straight bolt-on with basic hand tools.

What prep work is required before painting?

Sand and prep the surface before applying your chosen finish. FRP ships raw FRP, so light sanding with standard grit and a wipe-down will ready it for primer and paint application.