Arcs and pings
On the arcs and the pings, the published arc represents points on the earth's surface which are equidistant from the satellite and where the aircraft could be - we understand this was from the last ping received.
If, during its flight, the aircraft had been at some point, other than on the published arc, an earlier ping would have shown this - with a concentric arc of different radius - this would be pretty valuable information giving further hints as to speed and direction e.g. if two arcs an hour apart had almost the same radius then it's pretty likely the aircraft's path would have been substantially along that arc.
Again, if transit times for the earlier pings are available, all such data will surely have been already extracted but, seemingly, not yet published.