Do I need new fasteners when I install this gasket?

Reuse your factory header bolts if they're in good shape — this gasket compresses cleanly on stock fasteners. If your bolts are corroded or stripped, grab a fresh set rated for exhaust manifold duty to avoid repeat leaks.

Should I apply any sealant or compound to the gasket before bolting it down?

Dry install is fine — the gasket seals under bolt pressure alone. If you want extra insurance against micro-leaks, a light coat of high-temp gasket maker on both sides doesn't hurt, but it's not required.

Can I reuse the old header gasket, or does this need to be replaced?

Once a header gasket is unbolted, it loses its sealing bite and compression memory — replace it every time you pull the manifold. Installing a fresh gasket now saves you a second teardown in three months when exhaust noise starts creeping back in.