Do I need hardware to install this, or does it come with bolts?

The bracket assembly is included. Hardware is not confirmed — check what fasteners are already at your factory mounting points before installation, or have M6 bolts on hand as a backup.

Will this fit if my car has a front bumper undertray or splash guard?

Installation uses factory points on the frame itself, so aftermarket undertrays shouldn't interfere. Test-fit first — if your splash guard blocks access, you may need to remove or adjust it temporarily.

Can I paint this bracket to match my bumper if I want to?

It's hard panel material, so it's paintable if you want a custom look. Clean and sand the surface lightly before priming and painting to ensure adhesion.