construct a closed loop control VI using a mean value

Dear all

I want to use a mean value of 20000 samples as a feedback signal to construct a PID controller. That means I will acquire 20000 samples in each loop, and the difference between the mean value of these samples and the set point is used as the input of the pid controller, the output of the pid controller is used as the amplitude of a sinewave signal. The example VI is in the attachment.

The question is :

(1) All the examples in the NI samples related to closed loop control are one channel ONE sample (read), so is the write part, can I use a one channel N samples in the loop for the read and write?

(2) If the I use "one channel N samples" in the read and write module, what is the loop time for this VI, does the loop time equal to the time consuming of  data aquire and data generation?

Thanks for your attention!

Mr. Wu