Do these mount at the factory fog light locations?

Yes. These sit at factory mounting points—no drilling or bracket fabrication needed. Bolts straight in where the blanks were.

What bulbs do I need to buy separately?

Bulb type and wattage aren't specified in the product data. Check your vehicle's service manual or test-fit the housing to confirm the socket type before ordering.

Does the switch wire into the factory electrical harness?

The switch is included and dash-mounted, but wiring method depends on your comfort level. Most installers run power and ground separately or splice into existing circuits—refer to a wiring diagram for your model year.