You may already know about this site. He makes a kit to handle biodiesel. He gives a pretty good explanation of how and why of heating the system. Maybe you can p/u some ideas here or buy a kit.
There are several sites on making biodiesel that explain how to take the soaps out to prevent...
The 2X branch areas is the better approach and does minimize maldistribution. 1-1/2X header is the minimum. References in TEMA, API etc provide an initial guidance in this regard.
