Will I need to drill out fog light cutouts myself, or are they pre-cut?

This bumper does not ship with pre-drilled fog holes. You'll need to mark and cut the openings to match your fog light kit or OEM placement. Dry-fit first, then mark and drill from the back side to avoid chipping the front face.

Does the lower valance have sensor or bumper support holes already in it?

The raw design does not include pre-drilled sensor cutouts. If your car runs a parking sensor, you'll need to carefully cut the hole after fitment. The valance is solid FRP, so take your time with a rotary tool and fine bit to avoid cracking.

What prep work is needed before painting?

Since it Requires Surface Prep, inspect the surface for any dust or debris, lightly sand if needed, then apply your base coat and clear. No additional primer layer is required unless you prefer extra build. Follow your paint manufacturer's cure time before installation.