Will this plug into my factory wiring, or do I need an aftermarket relay?

The switch integrates into the kit, so you're not hunting down a separate relay. Tap into your truck's existing electrical harness at the dash—the included switch gives you direct control. Your truck's manual will show you where to pull power and ground.

Do I need to drill or modify my bumper to install these?

No drilling. These are designed for factory mounting points, so they sit in the existing fog light locations on your bumper. If your truck came equipped with fog lights originally, the cavities are already there.

What if a bulb burns out—can I replace it myself?

Yes. Once installed, bulbs are accessible from behind the housing. You'll need to remove the trim panel or fascia trim to reach the back of the assembly, but bulb replacement is a straightforward swap.