Do I need to clean or prep the manifold and head surfaces before installation?

Yes. Remove all old gasket material and carbon buildup from both the exhaust manifold face and cylinder head port. A clean, flat surface ensures a proper seal. Use a gasket scraper and solvent; avoid wire wheels that can gouge the aluminum.

What hardware comes with this gasket?

The gasket itself is included. Header bolts and fasteners are not confirmed — source those separately or verify they're in your manifold kit. Gasket alone does not include bolts.

Can I reuse the old header bolts, or do I need new ones?

Header bolts can lose tension over time and heat cycles. If you're replacing the gasket, new bolts are the smart move to avoid exhaust leaks down the road. Check your engine manual for bolt size and torque spec.