Do I need fasteners to install these, or does anything come with them?

Hardware is not included with this set. You'll need to retain the factory fasteners from your existing regulators, or source new hardware that matches your vehicle's door panel setup.

Will these work if I'm only replacing one door window?

This is a pair set—both motor and regulator for driver and passenger doors. You can install just one side and store the other, but you're buying both units.

What's the actual installation process—do I need to drop the door panel?

Yes. You'll remove the door panel, unbolt the old regulator assembly, disconnect the motor harness, then bolt in the new unit and reconnect. Factory mounting points align with your existing door structure—no drilling.