Regarding the 0.47 ohm resistor.

As it's in the ground leg am I not correct in thinking the power rating is different, as it's current is say, 1amp, but it's the voltage drop across the resistor that counts which is in mV.

Put it this way with real world on the board. On the positive output it ran quite warm at 1amp. In the ground leg it is still cold at 1amp.