I would be careful just connecting the wires up and seeing what happens. Generally the fuel / oil temp use a resistive voltage, so say read between 2v and 12v for empty and full (just an example). These can be different per car and may be alot less or more volts. Normally the Rev / Speedo work off a constant voltage with a variable frequency, which lends itself easily to pulse-width modulation. So you would read the time between each pulse and that would then convert into rpm or mph. These can differ greatly between cars. On the MR2 the pulse also links into things like the fuel pump (runs at a lower voltage on tick over) and on the ECU it brings in the speed limiter on imports. You will then have all your warning bulbs but they should'nt be that tricky really.