Will this work with my truck's existing hitch receiver?

Yes — as long as you have a standard 2" receiver. It mounts using the same pin hole, so no modifications to your hitch or bumper needed.

Does it come with the pin and hardware to mount it?

The assembly comes with the step bar itself. You'll use your existing hitch pin to secure it. Check your truck's manual for any additional fasteners you may need for your specific setup.

Can I paint this before installing it?

You can prep and paint it ahead of time if you prefer. Let any finish cure fully before mounting to avoid wear marks against the receiver.