Take it easy bud, this visa is made for long stays and multiple entries. Applicants are also thoroughly vetted. I would be sweating much more entering visa exempt. It will be fine... just answer their questions if they ask something, I would bring all supporting documents just in case.

I dont know what you are asking really. If you have a contract then yes, you can apply for workcation. It seems you dont have the 500k THB in your account yet if I understand you correctly? I am confused. But you need 1) a employment contract stating you can work online 2) 500k or equivalent in your bank account. How much income you make is irrelevant, at least as of now.