Do these headers require gaskets or seals?

Yes. You'll need header gaskets to seal the connection at the cylinder head. Standard big block gaskets are readily available — confirm your engine displacement to order the correct set.

What fasteners do I need to mount these?

The listing does not specify mounting bolt type or quantity. Refer to your vehicle's service manual for the correct fastener specs, or measure the bolt holes during mock-up before ordering.

Do I need to apply heat coating or paint before installation?

Stainless steel will develop surface oxidation and patina over time — this is normal. If you prefer a finished appearance, ceramic or high-temp paint can be applied before install. Headers will reach 500+ degrees under load, so use only heat-rated products rated above 1200 degrees Fahrenheit.