2) All or several pings measured the same distance to the aircraft. This would mean the aircraft was either stationary or flying exactly along the equi-distant radius to the satellite.
It wouldn't even tell us that as it is feasible that the track flown could be backwards and forwards across the line. Pretty unlikely granted, but with a +/-5km error it is not outside the bounds of probability.
I accept however that the final two pings being the same distance from the satellite would strongly suggest a stationary aircraft and more coincident arcs than that would suggest the aircraft is on land and not in the process of sinking or drifting and therefore likely to be on the 'northern arc'. Those are the only conditions that I see the prior pings being of any help to the search.