Impacts and Craters
Yes, many times.
We assume so, but we have no evidence as the Pacific floor has been resurfaced by molten material from the earth’s interior.
The biggest crater we are aware of on land is the MAPCIS structure which takes up most of Australia. It is 1300 miles across (diameter).
Probably the one that caused the MAPCIS structure. It must have been massive, but we really don’t have any way of determining how massive. The one that caused the Chixulub Crater in the Caribbean was about 20-30 MILES across.
No, it is covered over with other sediments.
It dates from about 65 million atomic years old, or about 5050 years ago. It is 190 miles wide.
Both. The “Ring of Cenotes” shows where the crater rim is on land. The ring showing the limit of ejecta is how far material flew out when the asteroid hit.