Will this interfere with trailer hitch installation?

Depends on your hitch design and receiver height. Test-fit the hitch with the reinforcement bar in place before finalizing mounting. Some Class II hitches mount higher and clear without issue; others may require spacing shims.

Do I need to prime or paint this before installing?

The bar ships unpainted. Paint or prime it before bolting on if you want color-matched finish; otherwise, apply protective coating after install to prevent corrosion.

Are fasteners included, or do I need to source my own?

Hardware is not included with this assembly. You'll need to source bolts, washers, and lock nuts that match your factory mounting points—refer to your service manual for the correct specifications and torque values.