Speaking to the "who is using the most bandwidth at any given minute" there currently isnt an easy way to do so. In 7.1.6 we did get the ability to reset the dashboard information, but then you would lose historical information.
I'm guessing you are wondering who is making the requests to the "address of the site that is currently using the most bandwidth", correct"? If so, I dont see a way in the dashboard, it could be correlated using the access log. Alternativley, there are dashboards for "Source IPs by Bytes Transferred" and "Source IPs by Number Of Requests", this could point you in the right direction as to the "who" in this situation is. Btw, these are located under Dashboard > Charts and Tables > Traffic Volume.