Oxygen Sensor Question ECU 1997 Subaru 2.2L EFI Conversion

[Ramjet]

I'm adding EFI to a Carbureted 2.2L with a manifold and ECU from a 1997 Brighton Legacy.
The engine is in a RAF 2000 Gyroplane.

(1) Why are Oxygen sensor Heaters connected all the time the ignition is on? Does the exhaust not keep it hot enough even when at low idle or extremely cold outside air temperatures?

(2) Does the Rear oxygen Sensor wire need 4.5volts in order for the ECU to provide best fuel economy /appropriate mixture for the power setting?

(3) Pin 87 on my ECU diagram shows "empty" but its not, it has a brown wire with a single silver bar. Would anyone know what this is for?
The ECU is a DA0 8D version 5720

(4) Starter switch Pin 86
Does this take power from the starter Solenoid?

(5) Test Mode Connector , is normal with 5V or Ground?

(6) Vehicle Speed Sensor - This looks like the output of a Hall effect sensor, what is that sensor? is it off the gear box? Diff? Wheel axel?

(7) Engine Knock Sensor
Does this need to be connected for normal operation? If it is not connected will the engine otherwise run normally?

(8) What is the current drain of the ECU when the ignition is on?

[richie2990]

From my dealing with these cars for over 10 years , the upstream 02 sensor heater is pwm if you look on a scope and it measures the current , at idle the exhaust is not hot enough to keep the 02 sensor hot enough , i have never measured it under hard driving , but WOT it will be ignored by the ECU , it uses a PTC so as it gets really hot the resistance goes up and the current goes down so the heater doesn't melt, down stream 02 sensor normally has nothing to do with fuel trims just cat converter efficiency , yes you need a knock sensor other wise the ECU will pull the timming , it has a bias voltage which the knock sensor modifies it and with out it you will have a high voltage code , always go bosh OEM for subaru sensors otherwise it will act weird and you will end up chasing something else , i am just guessing but maybe 1 to 4 amps for the ECU power consumption , the data line is around 5 volts if i remember right , the speed sensor is a 3 wire hall effect sensor and is located on the side of the gearbox