I don't know for sure, but I think the list of viewers is based on most recently viewed. That's been my observation, anyway.
Also from observation, the date range only affects the graph displaying the number of views, and not any of the other information presented.
Looking forward to hearing an "official" answer.
I checked with one of our developers and it looks as though the "viewers" list is organized alphabetically but by last name first. I believe, if the last name isn't share/shown, then it would default to then look at the first name or username. Hope this helps.