[JSeery]

"Is there risk of fuel leaking internally on the stock fuel pump when using the electric?"

Yes, if there is a rupture of the diaphragm in the mechanical pump it will pump fuel into the engine.

"I do plan on adding an adjustable pressure regulator."

There are some cheap regulators that are just that, cheap. I would use a quality regulator.

I don't know if the Carter pumps are draw-through or not, but I don't think they are.