1. Compatibility with pico psu. The distribution board will use a load sensing circuit to turn on a load switch (or relay) to distribute 12V power to PCIE outs. However 12V rail will still be on on the input side. Positive is less wires.
Yes, yes, YES! I was thinking about exactly this yesterday. It seems like such an obvious answer for adding a power hungry GPU to the simplicity of the Direct-plug ATX solutions.