Will these mount at the factory fog light locations without drilling?

Yes. These are designed to fit the OEM fog light cutouts on 4-door models—no modifications needed to the bumper or frame.

Do I need to run new wiring, or does the switch tap into existing harness?

The switch is included and designed for straightforward installation. Wire routing and connection points follow factory logic, but you'll want to consult your vehicle service manual for exact harness locations and tap points.

Can I replace just one bulb, or do they come as a matched pair?

Both H11 bulbs are included with the kit. You can replace individual bulbs later using standard H11 replacements from any auto parts retailer.