To Ding's list, I propose adding #11: (related to #7)
"Quotes their own writings more frequently than, and as equally authoritative to, other widely accepted sources used by non-members." In this case, they quote the Watchtower and and various books published by WTBTS as if they were accepted scripture. Note well: they call the weekly meeting a Watchtower study rather than a Bible study.
Yes, it is a cult. No, it does no good to tell a Witness that it is a cult. All that does is solidify their resistance to anything else you say, which they might otherwise make some attempt to hear.