Do these bolt straight to the factory head studs?

Yes. These use stock mounting points — no modification needed. You'll want to have new gaskets and studs on hand since you're breaking the original seal.

Does this header come with the gasket and hardware?

Header assembly only. Grab a header gasket and stud kit rated for your engine — they're cheap insurance against leaks and make reinstall cleaner down the road.

Will I need to clearance anything under the car or reroute lines?

Mounting method is factory-spec, so clearance should match OEM expectations. Test-fit before final tightening to confirm no interference with heat shields, lines, or suspension components in your specific setup.