The route that it flies - straight line, circles, wiggles etc is irrelevant provided it stays within the permitted area.
Depends on route I'd say.
Some particular routes like over Himalaya require specific escape route thus the route becomes a factor. Even though one stays within the approved circle the real diversion will be outside the limits. I remember a particular case with 120 min etops flight via northern Chinese corridor where at some point between the Pakistan and China a diversion back to Chinese ETOPS alternate using DIR TO wans't an option obviously due to terrain. If I recall correctly highest Grid Mora was around 31000 ft.
