You may be right about that. Looking over the materials I got when I purchased the car, they had changed the overflow tank - there's my source of missing coolant. Since I did not get a low coolant light, I am going to check the sensor.

Regarding the fan speed - I can tell you without a doubt that the fan speed on MY car is variable. It may take unusually high engine temperatures to raise the speed - let's hope that is something that most owners have just not experienced.