Does this come with bolts and fasteners?

Just the bracket itself. You'll use the existing factory bolt holes on your frame and the studs on the bumper cover—no additional hardware needed for installation.

Will I need the passenger-side bracket too, or does one work for both sides?

This is the left-side bracket only. If your bumper cover is sagging or loose on the right side as well, order the right-side bracket separately. Both are needed for full support on most installs.

Can I paint this before or after installing it?

Install first, then paint. It's easier to mask and spray once it's bolted in place and aligned with the rest of your bumper assembly. Prep the surface with light scuffing and primer as you would any plastic panel.