Do I need new hardware to install this gasket?

Check your header bolt condition before assembly. If bolts are stretched or corroded, replacing them prevents leaks from returning. Most builders source new hardware when doing header work.

Should I use any sealant with this gasket?

The gasket is designed to seal alone — no additional sealant needed. Proper bolt torque and even clamping pressure are what make the seal work. Refer to your vehicle's service manual for correct torque specs.

Can I reuse my old gasket if I pull the header off again?

No. Exhaust gaskets compress permanently once installed and lose sealing ability on reinstall. Plan on a fresh gasket every time you remove the header.