Hey I can answer some questions of yours probably while I don't currently have efi I have researched a lot on it as it's in my plans.
-no info on fast efi I know allot of guys have ran megasquirt so you could probably get someone to give you a tune to start with if you went with that route.
-the manifold won't need to be heated because the fuel is being injected straight into the cylinders so there is no need to heat the manifold like you would for a carb.
-headers while custom from a local shop may be an option there are multiple companies that already make headers. Some cast and some tubular. I really like cliffords headers personally.
