Do I need fasteners to install this, or does it come with hardware?

Hardware is not included with this handle. You'll need to source fasteners compatible with your vehicle's factory mounting holes — check your service manual or contact the dealer parts department for the exact spec.

Will this fit the passenger side rear door, or is it left-side only?

This is engineered for the driver side rear door only. The geometry and mounting points are specific to that location — passenger side requires a separate part.

Can I repaint this if I want a different color?

The textured black finish can be painted over with proper prep — scuff the surface lightly and prime before applying your color of choice. Test on a small area first to ensure adhesion.