Does the ABS light come on as soon as you switch on the ignition, or after you start to drive the car.

If the speedo doesn't work and you get an ABS light, possibly the problems are related. ABS gets it's base-line readings from speed sensors at the wheels. Interrupt those readings and the light comes on. However, I think the speedo is driven from a sensor on the transmission.

I'd pull codes for the ABS and see what that system reports.

Hope you've got the reverse-leads issue well documented with the dingbat that boosted your car. It is possible that the reverse polarity has fried something and that will cost $$$.

To test the instrument cluster, you should find a small "button" in the center of the knob used to set the clock. Start the car. With the tip of a pen or paperclip, press the button for at least 5 seconds. The odometer display should show ------------- when the cluster goes into test mode. Within 5 seconds, pull out on the clock setting knob and rotate briefly to the right. To move from one mode to the next, pull the knob out again and rotate briefly to the right.

There are 9 testing modes for the cluster
1 - shows gas tank size (odometer will read 1 80 for an 80-litre fuel tank)
2 - momentary fuel consumption in litres per hour
3 - engine oil pressure in bar
4 - engine rpm
5 - engine oil level (0 = level OK, 1 = not OK)
6 - activates oil pressure, economy, tach, speedo, fuel level gauges to 1st quarter of travel - display also reads resistance of outside temp gauge in K ohms
7 - oil pressure, economy, tach, speedo and fuel level move to 2nd quarter of travel
8 - economy, tach, speedo and fuel level move to 3rd quarter of travel. Oil pressure remains at 2nd quarter.
9 - tach, speedo and fuel level move to 4th quarter of travel - oil pressure remains at 2nd quarter, economy remains at 3rd quarter.

This test should allow you to figure out whether the cluster has a problem, or whether the speed sender in the tranny is the culprit.