PiSupply reverse engineering
Why is the normally-connected part of the SPDT switch connected to the capacitor/transistor part of the circuit at all?


To provide initial current to transistor's base, until the RPi gets powered.


  Why are there two transistors in the circuit?


Because 1 transistor doesn't amplify the current enough.


  Why is there a resistor and ground by the SOFT_OFF?


To pull down that line to 0 V when the button is not pressed.


  What's going on with the relay coil being connected with a diode?


To absorb current from relay coil when transistors shut it down.