if over 50, why not get a Non O before you arrive? That gives you 90 days and you can arrange a year extension on it for 1900THB... the same price you would pay for a 30 day extension on the tourist visa. Canada still does an affidavit of income letter so you wouldn't need to bank the required funds in Thailand, just a visit to the consulate or the embassy in Thailand. Having the 90 days also allows you the option to open a Thai bank account for ease of paying for day to day expenses. You can get re-entry permit on the visa so you can leave when you want and as long you as come back before the visa expires it's another easy entry. If in Manitoba and West you apply online through the Vancouver consulate, who are great to deal with.
You currently can't get this visa when in Thailand, unless you do so fraudulently. Either get it before your arrive or leave and apply at a neighboring country. It is extremely easy to do yourself and agents fees are all over the place, some as high as 70K THB not including your actual 10K THB visa cost.
it entirely depends on the embassy you apply through as they can have different requirements. Some require a dependent to show the 500K THB other don't. Some want 500K THB per person in the account if it's a join account, other don't. You need to look at the embassy you are applying through and what their requirements are.
Yes, if you stay 180+ you are deemed a tax resident. No one, except maybe an international tax accountant, can answer if you'll pay tax or what you'll pay tax on because it depends entirely on factors like does your country have a tax treaty, your earnings, which country files taxes first and so many other things. Get an account and read the numerous other posts in this group that discuss this.
it's Ellie and she is one of the mods in the other popular but more strictly moderated group. They created the faq pages to use instead of having to answer the same questions over and over again.
if you employer is based abroad you can apply for the DTV Remote Worker category. You need to follow the requirements for the embassy you are applying at and submit those documents. You need to show the equivalent of 500k THB in your personal bank account and some embassies want 3-6 months of bank statements. If you don't have the funds, you could look at the sponsorship route. The funds have to be a liquid asset crypto and investments are not accepted.
Contact the owner of the group, they are an agent and can explain it better then I ever could. My very basic understanding is that for a fee, they meet you at some point prior to immigration and help you go through the process.
If you want to avoid the minibus fly but consider paying an agent to meet you and "help" you through immigration. Talk to the agent owner of this group, they'll have options available.