We are CO Elites and Premium has shown up on our NW boarding passes whenever we are upgraded (probably about two dozen segments since the alliance).
It did not show the time we were forced to ride in back.
I don't know what FQTV means, but it only shows on direct flights or on the first leg of a connecting itinerary. In that case, any following segments will say "Connection" in that same area of the boarding pass.