Yes. If you spend 180 days or more inside Thailand in any calendar year then you are a Thai tax resident in that year. If you are due to pay tax you must do so by the end of March the following year. How much tax you have to pay, if any, will depend on how much income you bring into Thailand that year, whether you can claim for any tax already paid in another country and so on
the problem will be if the embassy wants to verify you are still in the country you applied from or if they want to call you in for interview. Thai embassies don't expect you to travel in advance of a visa application being completed, they treat the application in the same way as previously in that they treat it exactly the same as if you physically handed over your passport
the next thing I got after that was a confirmation of receipt of application via email only 2 days after my card was charged. Then a further 2 days i was notified of approval texted to my UK mobile (I provided both UK and Thai numbers) and also sent to my email address
Thailand is severely cracking down on multiple visa exempt entries. You will likely have the same issue wherever you fly into. Either buy a visa that fits your purpose of stay before returning or find a fast track service at one of the airports that will guarantee you entry
check your spam folder. I recently renewed mine and had regular updates throughout the process. Sent to UK by VFS on 4th Feb and back with VFS on the 20th Feb.