Do you have temperature gauge (reads actual temperature) or just a temperature switch. If it's a gauge, disconnect the wire to the sensor and turn your ignition on (not run). The needle should go maximum. Then short out the wire to ground, it should read minimum. If one or both indications do not happen, you have a defective sensor.
I don't think your problem with the temperature is related to your power steering noise. If the noise was not there prior to your 100k service but appeared after, then what was done more than likely caused the noise. Maybe the belt was too tight or not lined up right. Then again your power steering pump maybe on its way out. With the engine running spray water on the power steering flywheel and see if the noise changes or disappears. If it does then your problem could be an improperly installed belt. The new water pump is an unlikely cause simply because it was new. But don't disregard this completely as a possible cause.
