I can answer my own question now. My flight was delayed so I stayed at the airport from 11am till 6pm.

The restaurant remained open while I was there, even after the YOW flight departed. The shop was closed around the time YOW flight was boarding. There is another shop inside the post security area. The post security area opened around 2 hours before the YOW flight. There were few vending machines too, and water fountains. Yummy Shawarma is about 15-20 minute walk away.

YOW and YUL flights are the only flights require security check. Flights within the territories (including YZF) do not require security, and you can bring large quantity of liquid if you wish, such as large water bottles.

Gate 1-3 are for flights requiring security check, gate 4 is a swing gate, which is mostly used for YOW-YFB-YRT-YZF flight.



And on another note, I spent 5 nights at Iqaluit and I really enjoyed my stay.