About the fuel shut off!
All fuel injected cars have some type of fuel shutoff in case of an accident. In the case you cited, the oil pressure switch does not, in itself, shut off the fuel pump. It sends a signal to the computer and if certain conditions are met, the computer will shut off the fuel pump. The primary way the computer knows that the engine is running is from a reference signal from the distributor. The ECU will not allow any fuel supply until it receives distributor reference pulses. As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil pressure indicator or gage on the instrument cluster, and the other is a normally open switch which closes when oil pressure reaches about28 kPa (4 psi). If the fuel pump relay fails, the fuel pump switch and engine oil pressure sensor runs the fuel pump.