Do I need to remove the door panel to install this?

Yes. Door panel removal is required to access the regulator mounting bolts. This is standard for any window motor replacement on this platform. Plan for basic hand tools and a trim panel removal kit.

Will this work if only my motor is bad, or do I have to replace the whole assembly?

This is a combined motor-and-regulator unit, so you're replacing both at once. That's actually the safer move—if one fails, the other typically isn't far behind, and you avoid a second tear-down later.

What fasteners come with this?

The assembly itself ships as a complete unit. Verify your door panel bolt count before ordering hardware separately—most applications use standard M6 or M8 bolts that you may already have on hand from the old regulator.