If you can use just 12V, go that route.
Looking at the pictures on their website, it would appear that this fan controller works by decreasing the voltage supplied to the fan. If this is the case, I would strongly recommend against using this to control the fan. The PS3 fan is designed to get full supply voltage all the time, and to be controlled by a PWM signal. Using supply voltage to control the fan speed will work fine at first, but will burn out the fan motor over time, and eventually the fan will just stop.
As for the RPM data, it is a bit tricky with a PS3 fan because there is no actual RPM data line available. It is possible to measure RPM by the small pulses on the ground line going to the fan, but no pre-made device is going to do that since you need to write the code for such a device for the specific fan being monitored. For my mods, the fan speed percentage displayed is just what my mod is sending to the fan...and is never read or adapted from RPMs.