Prime & Paint underside questions

Thanks Again for some of the previous answers FABO members have given me in the past. I'm working on a 68 Dart. The underside of the car is a mix of rusty, but solid framerails, good floorpans with factory primer/coating, AMD trunk pan with black EDP coating, & bare metal US CarTool sub frame connectors.
Do I prime the bare metal with Etching Primer, then POR15 to seal them before painting, then use regular primer over the factory coating, & the AMD parts, then put POR 15 over that and the rusty parts?
POR 15 the whole shebang, including the bare metal, then cover that with Epoxy primer then paint?
What is Lizard Skin that I have heard of, & where does that fit into all those other options?
How about recommendations for primers, sealers, etching primer, epoxy primer, etc.
Thanks,
:burnout:
Get a grip & let it rip