Will this reinforcement bar interfere with a trailer hitch or rear sensors?

The bar is designed to mount behind the bumper assembly itself. If you're running a trailer hitch or have parking sensors, verify clearance during test-fit before final installation — the bar sits at the factory mounting zone but doesn't account for aftermarket hitch hardware.

Does this require painting before installation?

The bar ships with a factory-finish surface. Whether you paint it depends on your visibility preference — some bolt it in as-is if it's hidden behind the bumper cover, others prefer to match the bumper color for a finished look if any edge is exposed.

What fasteners do I need to install this?

The bar mounts at factory attachment points, but hardware type and size aren't specified with this part. Grab a bolt and washer set that matches your Altima's factory rear bumper hardware gauge, or reference your service manual for OEM specs.