Will this interfere with my trunk seal or rear bumper clips?

No. This is a front lip mounted to your front bumper using factory points. It sits in front of the grille and hood area — nowhere near trunk seals or rear components. Once fastened to the factory mounting locations, clearance is set.

Do I need to drill new holes, or does it use the existing factory holes?

This design uses your factory mounting points, so drilling is not required. Verify your vehicle's existing fastener locations before installation and use appropriate fasteners for your bumper type.

How should I prep this before painting?

Sand the primer surface lightly to rough up the finish, then clean away all dust with a tack cloth. Apply your chosen primer and paint per the product instructions for your coating system. The FRP surface accepts standard automotive finishes.