Do these bolt directly to my truck without any modifications?

Yes. They mount at factory rocker points with no drilling or bracket fabrication required. Existing fasteners work.

Are the LEDs already wired, or do I need to splice into the harness?

These use standard OEM connectors that plug directly into your truck's existing wiring. No splicing needed.

Will the chrome finish hold up to road salt and weather?

Chrome resists corrosion better than bare plastic, but like any exterior trim, rinse periodically in winter climates to extend the finish life.