Definitely a safe country for anybody to move to, but it’s like everywhere else, once you’re living here on a budget, and aren’t a tourist, they’ll be a lot of days just sitting home, so you’ll have to figure out how not to be bored.
You get the OA from Canada through your Thai embassy there on the evisa website. You can verify funds through your Canada bank, then enter Thailand with a one year stamp. You’ll need health insurance for one year (check out AXA they have a cheap option that works for that purpose), and a medical certificate and a criminal background report. It’s pretty easy, I did it last year from the U.S.
Get a K1 finance Visa and get married in the states. I did it in 2017 and haven’t regretted it. You can do it yourself using Visa Journey where they have a step by step guide and forums to ask questions from others. Good luck.
Not free. In fact, travel expense to the border would be more than the 1900 baht fee for the extension at immigration, and a lot more time than it takes to just go to immigration. Didn’t make sense to me.