Regarding question 3, this would have been shot during the Spring climbing season. This year had an unusually long period of calm weather, which allowed the ~250 climbers and ~600 Sherpas to summit over the course of 12 days.

The vast majority of climbers ascend from the southeast route (from Nepal), with a smaller number ascending from the northeast (Tibetan) route. I can't tell for sure which direction the drone is flying in, but some clever piloting may have helped here.