MySQL: How to calculate potential wait time?
Is this saying the average wait time is 3.2s and occurred 11,543 times
  for a total of approximately 10.5hrs of aggregate wait time?


No, this is saying the wait occurred 11,543 times for a total aggregated wait of 3.2s.
The average wait time is then 3.2s / 11,543, or 0.285 milliseconds.

Note that every file io call, including file open, read, seek, close, read, write, etc is counted, and that what is measured is FILE io (at the OS level), not DISK io (at the hardware level).

Disclosure: I happen to work at MySQL, and I am the author of the performance schema.