If I fly by Canada Air, is the baggage claim system the same as the US?

I'm planning to go on a trip to Canada to visit my friend in the coning weeks -- however, I'm a minor (17.) I have a stamped/notarized permission slip from my parent, my birth certificate, and passport. However, I have since been informed that the baggage claim system in Canada is different from the ones in the USA, and I did not use the "unacompanied minor" option when buying my ticket, as I'd read on the airport+border control's website that, as I was above the age of 16, that I didn't need to register as an unacompanied minor and it was optional. What do I need to know? How would I go about retrieving my baggage in the airport after the flight? Is it really different from retrieving it in the US? Will they not let me retrieve my baggae because I'm a minor?

If anyone needs to know, I'm flying to Toronto Pearson Airport.
Please answer quickly, I only have a few weeks before flying!

Can this bag be used as carry on? Has anyone used this bag as carry on?

Can my adidas® santiago v medium duffel bag be used as carry on luggage on my international flight to Haiti? Has anyone else used the bag as carry on? I feel like it ll be too long but I've never been on a flight or in an airport so I just need help.

Added (1). It is an American Airlines flight

How do I pay for checked luggage at an airport?

I'm flying with United out of Portland, OR to Santiago (Dominican Republic) on Thursday. I've already called United but all I got was a bot telling me stuff about lost luggage. I've heard that most airlines don't accept cash for checked luggage fees, and I've bought a $50 prepaid Visa to hopefully cover the fees. Turns out prepaid Visas can't be used internationally, and if that's all true then I have no way to cover my checked luggage fees on my returning flight from the DR. Can I use cash to cover checked luggage fees both domestically and internationally?

Is it weird that I like being on airplanes MORE than the actual vacation?

Being at airports, seeing people from different parts of the world together in one location, and the excitement of traveling is awesome. Going on airplanes is fun too because I'm high up in the air, about to go somewhere for vacation. But when I get to my destination, I feel less eager yet I don't know why. I just like being on airplanes. Sure, I like traveling around different countries and tasting different food, too, but being on airplanes is twice as fun for me.

Is it silly to purchase airline tickets months in advance?

I will be going to France with my parents(I'm fifteen) in April, which is about 5 months from now. I've checked Expedia, and the airline and airport stops of my choice are limited--only about five left. I want my parents to purchase it right now, but I'm not exactly sure if they can ask for days off work. I don't know. I'm scared that other people might book it before my parents can. Should I tell them to book it right now or later? Also, they can only cancel one day after. :/