engine electric system (sensors)

Hi,

I attempt to make a research internal combustion engine (petrol one) of an old lawn mower, so I could measure the engine power, efficiency etc under different fuels. (methane gas and gasoline-methanol mixture. both have higher compression ratio than gasoline so there will be no detonation problem)

I will place the MAF/IAT probe in the intake tube, wideband zirconia O2 probe and EGT sensor to the exhaust pipe. I attempt to get shaft RPM from a spark plug current.
I attempt to lead all sensors voltage to the analog to digital converter and then to the micro-controler where I will use the imput data to calculate
engine power, torque, thermal efficieny....

So here are my "guestions" (statements) - please read them first then correct me if I made a mistake:

MAF/IAT probe are basicaly two sensors - temperatue and hotwire resistance, so there should be 4 wires.
hot wire as I know works the way that the ECU apply the proper input voltage to one end so the output voltage is constant. mass flow is calculated from the input voltage.

IAT sensor as I know is thermistor type of sensor and change the electrical resistance with temperature. So the ECU apply constant input voltage to one end of the sensor and measure the output voltage on the other end.

wideband zirconia O2 sensor as I know has 5 wires.
one is ground, other is for heater, two are for fuel cell voltage output and last - fifth is for the gas pump. the sensor works so the ECU apply the proper voltage to the gas pump so the fuel cell output voltage stays constant all the time.

EGT sensor as I read on the net is not thermistor type but Thermocouples (http://en.wikipedia.org/wiki/Thermocouples) type of temp sensor. so ecu don't need to apply any current because the current is formed by the sensor itself. so ECU only measure output voltage.

on this site http://www.dp-engineering.nl/EN/products/sensors/ there are different sensors prices.