It's unfortunate ignorance on how credit cards work. A good number of people think you pay interest no matter what even if you pay it off, or they think you have to carry a balance and pay interest for it to help your credit.
Maybe not in Canada, but gas pump skimmers pop up all the time on the actual gas pump and public ATMs. Handing it to the attendant would be 10x safer. Not sure an attendant would be ballsy enough to run a skimmer right there.
I pay about $275 in annual fees. I more than cancel this out though. You have to do your due diligence before getting into multiple AF cards though.
Paying the statement balance alone is all you really need to do. Maybe make an additional payment if you made a giant purchase.
Yes. Don't buy stupid stuff you can't afford. It's not free money. At the very least get one and put your Netflix or whatever subscriptions on it. Set up auto pay on the card. At most put every single dollar on it, but just be responsible.