Do these bolt straight to the factory locations?

Yes. These are designed for the factory rear bumper opening with direct mounting to existing factory points — no drilling or frame work required.

Will I need to source my own wiring harness?

Wiring harness is not included with these lights. You'll need to run power from your battery or auxiliary switch and ground to chassis — fairly straightforward with basic tools and a wire stripper.

Can these be installed by a beginner?

The mounting itself is simple bolt-on work. Wiring is where most DIYers get hung up — run power, ground, and a switch or relay tap. If you've done basic electrical work before, you'll be fine. If not, an hour at a shop is cheap insurance.