I'm pretty sure the 2 plugs with brown & blue/brown (LHS), and red & brown/white (RHS) from the dash are front speaker cables.
The white plug near the fuse box in the scuttle tray is for front fogs, and should be connected to the fog light switch 2nd position as standard - the foglight engine bay loom plugs into the white plug.
I believe the two earth cables bolted to the bulkhead would normally be connected to a bracket on the inlet manifold, one of which should be the lambda earth.
The main earth cables are supercharger to chassis, gearbox to chassis, battery to inner wing.
The black plug that is above the inlet manifold in your photo could be for the knock sensor or lambda, but to be honest there are several things that could be.