Will this interfere with the trunk or bumper seal?

No. The speed style profile maintains factory clearance at the bumper line. Your existing bumper seal sits undisturbed.

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

This lip uses factory mounting locations — no drilling required. Line up the mounting points on the underside with your existing bumper holes and bolt down.

What prep work is needed before painting?

Sand and prep the surface with your chosen grit before applying your finish. Wipe down with a tack cloth to remove dust, then apply your primer and paint system.