Do these lights need wiring to the factory harness, or are they plug-and-play?

The switch mounts at the dash and controls the lights directly. Check your vehicle's OEM wiring under the bumper to confirm connection points before installation.

Will these work if I don't have factory fog light openings on my bumper?

These are designed for the factory bumper openings. If your coupe doesn't have them cut out, you'll need to modify the bumper to fit the bezel.

Can I replace just the bulbs later, or is the whole unit sealed?

H11 bulbs are replaceable. Check the housing design once installed to confirm bulb access for future swaps.