In Canada you are required to present picture ID at the gate. If you are flying out of country the airline can demand to see a passport at check in as they are responsible for ensuring that they do not carry inadmissible passengers.
You do not need to show your id to the screener.
You may leave the screening process at any time if you choose not to fly that day.
In matters with the police foreigners have the same legal protections as any citizen of Canada.If you are arrested you must also be advised that you have the right to contact your consulate as part of the VCCR.
Police may be filmed as they are public servants performing their job in a public area.