Will this plug directly into my factory wiring harness?

Yes. The connector is OE-style and designed to mate with the factory radiator fan circuit without adapters or splicing. If wiring has been modified, test the connection before final installation.

Do I need to drain coolant before swapping this in?

No coolant drain is required. The assembly mounts to the radiator shroud, not the radiator itself. You're just unbolting the old fan and bolting the new one in place.

What if the fan doesn't turn on after installation?

Check the connector for corrosion and make sure it's fully seated. If the vehicle's thermostat is set low, the fan may not kick on until the engine warms up. Run the engine and watch the temperature gauge—the fan should engage around normal operating temperature.