because rock behaves like liquid at the time of impact.

it seems like craters of different side are roughly the same depth.

yes, about the same as when you idly throw small stones into the water

I was wondering that as well as the crater edges look smoothed... Billions of years of Space Dust? (Obviously a fresh impact crater would be starkly different, but if its craters are all from after it was formed, and then was still being inundated with a cloud of micro hits - and then the cloud of all the dust that was left from all the collisions turned to that powder, and finally settled over the surface.