Can the official stamp marks found on some documents be used as an "arrival" resource.
Yes, you can use the official stamped date. It shows in the example in Field Instructions that the stamped date is accepted.
Can you please share the batch code or number of this record?
The Field help states: The arrival place may be indicated on the line titled "Destined to." If the location is outside of Canada, mark the Arrival Place field blank. We only index what is shown on the "Destined" line.