Do I need to remove the entire bumper to install this retainer?

No — this bracket retainer typically clips into the existing factory mounting points on the left side. You won't need to drop the full bumper assembly unless you're doing other work underneath.

Does this come with fasteners or clips?

The retainer itself mounts at factory rocker points. Check that your vehicle still has the OEM clips in place; if any are missing or broken, source replacements before installation.

Will this work if I'm replacing a damaged bumper?

Yes — this retainer secures the bumper to the frame. If your old one snapped or cracked, this new plastic piece will lock the bumper down the same way the original did.