Do I need fasteners to install this to my receiver?

Fasteners are not listed as included. Bring the bar to your hitch and confirm the pin size and mounting holes, then source bolts or pins accordingly. Most 2" receivers use a standard pin and clip.

Will this step bar fit my truck if I already have a cargo carrier on the hitch?

The step bolts directly into a 2" receiver. If you run a carrier that also uses the receiver, you'll need to choose one or the other — they can't stack on the same pin.

Does the silver finish need any touch-up or maintenance?

The powder coat is sealed and designed to handle outdoor conditions. Rinse it with a hose after exposure to salt or mud to extend the finish. Touch-up paint isn't required unless the coating is chipped.