Any Asus R2E owners? Fan control system questions.

hello,

I'm looking at buying the Asus R2E, and would appreciate it if somebody could answer a few questions that I have.

For fan control of the chassis fans, which temperature does the motherboard refer to? Will the RPM's of the fans increase when the CPU temperature hits a certain threshold, or does it use another sensor?

Are the OPT 1, 2 and 3 fans controlled with reference to the OPT TEMP 1, 2, and 3 readings respectively?

As temperature increases, does the RPM of the fan increase steadily, or does it jump straight from low to high when it reaches a certain threshold?

Finally, when using the Fan Xpert utility to help control the fans, does the program always have to remain open? Or can you simply open it, dial in your settings, and then hit apply and close?

Many thanks in advance for any help!