Maybe? But you'd be better off asking in another forum. AC has no presence in T3. With that said, the purgatory area before customs/immigration in any airport I've been to has been barren and not a place I'd want to wait for longer than 30 seconds, looking shifty and guilty.

That seems about right (for an International arrival).

For what its worth, arriving from (many) places, including the USA on AC, the process to get to a AC domestic outbound is even easier, with no need to claim checked bags. Understanding your desire to help your friend, I'm not sure that is possible, and AC/US->AC/Can is pretty quick.