1. CAS = Cam angle sensor. This sensor tells the ECU the RPM and spark signals.
2. Left plug is the power transistor. Right plug is connects the coilpacks to the engine harness
3. Sensors on the thermostat, I only used one ofthem, believe it was the one on the right for the water temp sensor on the gauge cluster.
4. The holes behind the waterpump look normal to me. The pump has to be able to pump the coolant throughout the block.