Thanks PaulRB,
I contacted the ebay seller asking the details you mentioned. Regarding arduino Uno reading the fan speed, that is a good question. How can I setup Arduino to read a 4-pin pwm fan's speed? (This is the smaller 120mm fan)
I'll perform the temperature test within 24 hours . 
Because of shipping delays, it looks like the OLED display will be the last part of this project. So, 1st stage = get this Arduino Uno Fan Controller working without a display.