I have only done PVG once but there are check in counters and the concierge (younger guy) is usually there.
Seems to be standard on smaller international stations.
Usually, it is 3 hours before your flight is when it opens.
...and yes. Air China lounge is fine. 2 story lounge with OK food. I didn't do a ton of exploring while I was there but there was your usual shops around. I just hung out in the lounge until it was time to fly.