If you're in Canada, you need to apply through the Thai embassy in Canada. Alternatively, you could just say you're in the UK and apply through the Thai embassy in the UK.
Yes, you can work remotely as long as you're not working for a Thai company or being paid in Thailand. Teaching some kid online in China who pays you over PayPal has nothing to do with Thailand and isn't working in Thailand and there's not 1 single example of anyone ever being arrested or prosecuted.