The ping arcs only cover 4 to 5 hrs and a chang of direction thereafter is possible.
NO
The last known ping was at 8:11 am the next morning,
seven hours later. That ping means that aircraft MUST have been at least at that point. Given the fuel range, we can say for certain that it likely did not go much further than that unless it stopped an refueled along the way.
Up to 59 minutes error, so +/- 480nm plus glide distance of up to 120nm to 150nm. So add possible error of 630nm radius to those arc's in any direction.
NO. The ping happens in real time. The aircraft was on that arc somewhere at 8:11 AM. There is no margin of error.