Do I need gap filler or seam tape where the pieces meet the fenders and doors?

Yes. The side skirts and bumper pieces install as separate panels. Use flexible automotive seam sealer or gap filler at transition points to blend the kit with your existing body lines and prevent water intrusion.

Can I paint each piece separately or does the whole kit need to go together first?

You can paint each piece individually after prepping. In fact, most builders sand and paint the bumpers and skirts off the vehicle, then install them once cured. This gives you cleaner coverage on all surfaces.

What fastening method does this kit use — does it bolt to factory mounting points?

The kit is designed to use factory mounting locations on your vehicle. Verify your OEM bracket positions before assembly. You may need to source hardware separately depending on your existing anchor points and whether you're using factory clips, bolts, or custom brackets.