I can sympathize a little but...

1) I know how annoying it can be trying to sleep. I'm a pretty good airplane sleeper, I don't bring an eye mask because frankly I'm not concerned about getting a tight 8 hours in or anything. I'm always travelling for leisure so getting somewhere tired is fine for me. That said, it's damn annoying with the window shades. IAH-YYZ the other day, 7:40am flight, sure most people are up by now, but it's reasonable to want to sleep. I was in Row 12, with my window down, but the old couple across from me, or the 2 people behind them kept opening and closing their shades. I had half a mind to just ask "can you either keep it open or closed? I can sleep either way but the constant changes are annoying". If she had asked you to close it, she probably lied about people complaining, but she's also got experience and wants to avoid people complaining. I would've just closed it.

2) You're claustrophobic, I can't pretend to understand that, I just don't get it. I can't imagine how opening a window on an enclosed tube would help, but fine, if it helps then it helps.

3) If you're claustrophobic, shouldn't you take an aisle seat? Or if it's 3-3-3 an aisle seat in the middle section? Wouldn't that give you the illusion of the most open space possible? Either way your brain knows you're locked in this tube for 10+ hours and there's no changing that.

4) I can't say I've been to every country worldwide, not even close, but they all seem to play by different rules, so if you don't know, you've got to ask when it comes to bags. I know in Colombia I have to clear customs in Bogota, but not collect my bags. I know when I arrive in Toronto FROM Bogota, that I have to do both, then drop my bag at the connection desk for my flight to Vancouver. In Houston from Bogota, if I'm transferring to a domestic USA flight, I have to pick up, if I'm flying straight to Canada, I don't. So sure, it's complicated, but don't blame someone else for your mistakes.

5) Anytime you make a big mistake like that, there's not necessarily going to be a great set procedure to fix it. Which was your clock situation. I feel bad they didn't get to you faster, but again, would've been avoided had you done the correct thing with your bag. Had you originally proceeded off the aircraft and moved to where you should go right away, you likely would've made your flight, as you said it was only a 15 minute wait for your gate.

In the grand scheme of things, it sounds like your trip was highlighted by some not so friendly people, if that's the only thing that went wrong, I don't think you have any problems. The FA should've acted better, but you could've diffused the situation as well, the overhead lights are there for a reason. The agents on the ground aren't exactly the friendliest people but you shouldn't have really even interacted with them IMO. I think also when it's not Christmas, if you say you're going to Montreal, they'll just assume you're gonna miss the flight because they've got so many seats they know they can re-accommodate you easily. There's lots of reports out there about agents not being nice, so clearly there's some validity. I just don't share that experience, at WORST I've had indifferent service.