Will this lip interfere with the trunk when it opens?

No. The racer-style profile is designed to sit along the rear edge without blocking trunk access. Confirm clearance by test-fitting before final bonding or fastening.

Should I adhesive-bond this or drill mounting holes?

Both methods work. Adhesive offers a cleaner look and no permanent holes; drilling provides a more secure mechanical hold if you prefer future removal capability. Sand and prep the mounting surface thoroughly before applying your chosen installation method.

What surface prep is needed before painting?

Sand the surface with medium-grit paper to ensure proper paint adhesion. Clean off all dust, then apply your chosen primer and topcoat system. raw FRP takes standard automotive primers and paints without special treatment.