Will this plug straight into my door panel, or do I need to modify the wiring?

This uses the factory connector — no wiring modification needed. Simply unclip the old switch and plug in the new one. The harness is already there waiting for you.

Does this switch control all four windows or just the driver side?

This is the master switch, so it controls all four windows from the driver door. Passengers can still use their individual switches when this one is in normal mode.

What if the switch doesn't work after I install it?

Check that the connector is fully seated — a partial connection will kill function immediately. If it's fully seated and still dead, the issue is likely in the door wiring harness, not the switch itself. Test with a multimeter or have a shop verify power at the connector.