I didn't catch that bit of the presser... did he actually say 2022?
As an aside - I don't see how they can only open travel to 'select' countries... once you're out you're out! You can fly to SE Asia but once there catch a connecting flight to Europe.
As to your second question, this could be as simple as using the old smartraveller website for traffic lights. When travelling as far as I know, Government knows exactly where you are every minute of every day.
Now lets use smartraveller as the bible. Colours reflect COVID cases in each country.
Green - good to go. Sample being Singapore.
Yellow - test on arrival. Negative good to go. Reliant on better and faster tests in this case. Sample being Indonesia.
Orange - test on arrival, isolate at home and further test day 7. Sample being Spain.
Red - HQ. Sample being good old Seppo's.
If I fly to Singapore and back in 15 days all sweet.
If I fly to Singapore for 15 days, then 5 days in fly to Indonesia for a week, then fly back to Singapore then straight back to Australia, immigration would flag she has been outside a green country in the last 14 days. Been in a yellow zone within last 14 days and needs COVID test.
If I fly to Singapore for 15 days, then 5 days in fly to Los Angeles for a week, then fly back to Singapore then straight back to Australia, immigration would flag she has been outside a green country in the last 14 days. Been in a red zone within last 14 days and needs HQ.
Government can't control where you go when oversea's correct, but they KNOW exactly where you have been when you put you passport in those new passport scanners, and could be as simple as a green/yellow/orange/red flashing light to alert immigration officers.
This would of course slow re-entering the country a massive amount and require heaps more immigration workers (good outcome considering how many airline industry staff have been let go).
Greg Hunt himself a month ago stated the border will likely open gradually, not sure how that would work.