Do these mount to the factory bolt holes without drilling or modifications?

Yes. These are designed for direct fit at the factory mounting points on the rear panel. No drilling or frame work needed.

Will I need a wiring harness adapter or do they plug straight in?

Wiring compatibility depends on your truck's model year and existing harness. Check your OEM connector type before ordering—you may need an adapter to match the new housing plugs to your factory wiring.

Can I repaint the chrome bezel if I want a different color?

The chrome is a plated finish. Light sanding with fine grit followed by an automotive primer and paint will work, but test on a non-visible area first to ensure adhesion.