1 The Haynes manual is for UK built cars and doesn't necessarily apply to OZ built cars. Get an OZ w/shop manual with OZ wiring diagrams.
If I remember correctly, and I am NOT 100% certain on this, the way the wires are laid out is slightly different between MK1, MK1.5 and MK2 Cooper 'S' cars. The MK1 uses a different wiper motor to the MK1.5 and MK2 cars. The voltage stabilizer is also slightly different as the mounting bracket is different on MK 2 cars.
2 The 1 is an I (Instrument)
3 The E (earth) terminal is actually the metal case. It is attached to the metal body of the speedo housing. The speedo housing is connected to a body earth.
3 There are green wires everywhere. The supply from the fuse box goes to B (Battery). The supply to the wiper motor goes from B to the wiper motor. The supply to the 2 gauges goes from I to each gauge.
4 The voltage stabilizer is to supply an average 10 Volts to the fuel and temp gauges. The gauges work on a Bi-metallic strip principle. As the strip is heated it bends and alters the needle position. This is heated by a current dependant on the resistance of either the temp sensor or fuel tank sender. As the level of fuel or temp changes the current flow through the gauge changes and the heating of the Bi-metallic strip changes and hence the indication changes. This requires a constant voltage to work properly. The voltage stabilizer also works on a Bi-metallic principle and produces an AVERAGE voltage of approx 10 Volts. Because it is an AVERAGE voltage the instruments are very slow to respond otherwise the reading would change each time the Votage stabilizer output voltage varied.
The point of all this is that it doesn't matter which way you make the connections at the gauges.
Regards
RonR