1. Bridge ground wire - doesn't matter where it comes from - just needs to end at the bridge and form a connection (but not a loop) with all pots, the jack and the bridge.
2. Prewire should be fine - same as cats - many ways to skin a wiring diagram.

Colours of the wires change over time - the diagrams are indicative and I've coloured them to make the wires easier to follow. Otherwise we are playing with lots of grey and black lines that overlap.

Hope that helps.

B