Baggage and connecting flights on the same airline - Air Canada?

I have a connecting flight, both the same airline - Air Canada, from Trinidad and Tobago to Canada and then to Rome. Will Air Canada transport my luggage directly to Rome or will I have to collect and re-check my luggage in Canada for the connecting flight? If I'm paying for a 2nd checked luggage will I have to pay the fee twice? I emailed the airline but I'm asking here while I wait for a response.

Connecting through Montreal?

I'm flying international from the US but have a stop in Montreal with 2 hour layover. Is that long enough? I never gone through Canada before. Flying on air Canada.

Flight info and reservations?

So my friends and I are planning to go on this trip to Japan this year. We're coming from Vancouver Canada and our 1 friend booked all our tickets. He got the flight confirmation from Air Canada but it also said our seats weren't booked at all. We also had another friend who booked it separately than us and he mistakenly booked one of the seats we booked. Once he told us about this I kind of got worried as our seats might not be booked at all. So I checked the website that where my friend booked all our tickets from and the seats he booked were still available and the seat my other friend booked was actually booked. I keep telling my friend that he should call Air Canada but he keeps saying it's fine, maybe that's true I'm just worried once we get there there's going to be no seats left. I'm just writing this on what are your thoughts, and if this ever happened to you.