Do I need to drill holes or modify the bumper to mount these?

No—these are designed for factory fog light mounting points. If your truck came equipped with fog lights, the holes and wiring stub are already there.

Does the wiring harness connect to the factory electrical system?

Yes. The harness plugs directly into OEM wiring points—no splicing or aftermarket relay required. Run it behind the bumper the same way the factory design intended.

Will these fog lights work if my truck didn't come with fog lights from the factory?

If your F-150 has no fog light cutouts or wiring stubs, you'll need to drill mounting holes and route wiring separately. Test-fit the housing against your bumper before committing to permanent installation.