Traveling with a companion on AC C, HAV>YYZ, and then we are connecting to different flights. I've got a US passport and travel partner has a Thai passport. He has a Canadian transit visa. I'm continuing on to IAD on AC and he's going to ICN on AC. From looking at flightaware, it appears the flights from HAV arrive in YYZ T1, and both of our AC flights also leave from T1.

We're trying to figure a few things and will be grateful for any information:

1. When you arrive in Canada and are immediately connecting to an international flight, do you pass through any kind of immigration control, as if you're formally entering Canada, or just a security check for transit passengers?

2. Are US-bound flights segregated in some way from other international departures? Also at flightaware I see US flights departing from gates all over T1 so I'm trying to figure this out.

3. Basically since my flight leaves a lot later than his, we'd like to hang out near his gate until he departs and then I'll go over to my gate. Is this likely to be possible?

Thanks very much for any insights on this.