Very simple. Get a job first (find an employer who will employ you). Then they'll do the paperwork for you. But unless you have a profession that a Thai person cant replace you, you will have close to zero chance unfortunately
Right, so what's the whole idea of 'Tax return'?? Why do you need to provide that if they don't care whether you have income or not? Easy to just throw answers that are not true. Don't mislead people
Well if you apply on digital nomad pathway you'll need to provide income proof. If you go on soft power which means cooking classes or Muay Thai training or medical treatment you don't need to. All depends which pathway you select on your application