electric fuel pump wiring?

I don't know. Your description of C/ NO/ NC should work. The only difference is that you feed C to fire a relay instead of direct to pump. Not trying to talk down to you. C is like the center of a so called "2 way" 3 terminal switch. Whichever way the switch is thrown, one of the outer terminals connects to center which is "C" or "common."

So NO normally open, when there's no oil pressure, that contact goes nowhere

NC when there is no pressure that contact goes to C

So when the start relay fires, that should send power via NC and C off to the pump or pump relay

When the oil pressure comes up, the pressure switch flips, connecting NO to C. Now the power from NO feeds through C and powers the pump or relay, and the NC is now open (with pressure) and it goes nowhere