Will these mount at factory rocker points or do I need to drill?

These mount at factory points — no drilling required. Test-fit before wiring to confirm alignment with your bumper opening.

Does the switch connect to factory wiring or do I need an inline harness?

The switch and wiring method aren't detailed in the product specs. You may need to source a harness kit or splice into existing circuits depending on your Corolla's electrical setup — consult a wiring diagram or have an installer review the connections before starting.

Are these DOT approved for road use?

No certification markings are listed in the product data. If you're in a jurisdiction that requires DOT compliance for fog lights, verify local regulations before installation.