Will this work with my factory bumper, or do I need to replace the whole thing?

This trim bolts directly to your existing OEM bumper using the factory mounting points. You keep your bumper—you're just adding the SRT-8 style trim surround to it.

Do I need to cut any holes for fog lights or sensors?

Your factory fog light cutouts and sensor mounting remain untouched. This trim surrounds the lower section of the bumper and does not interfere with existing openings or electrical components.

What's the best way to prepare this for paint?

Light sand the primer-ready surface with 220–320 grit to break the gloss, wipe clean, and apply your choice of primer and paint. Follow standard automotive finishing practices for your selected paint system.