Yes, most airlines require a negative RT-PCR test result or you would not be allowed to board. I am flying SIA to Phuket in a few days and I heard that they are very strict about it.
It should not take too long. My husband who although, applied online (before this E-visa existed) and had to send his passport to the Thai Embassy, got his passport and visa back within a week or so. I’m pretty sure that you will get your E-visa soon.
I was advised by an officer at the consulate to use a gmail account and it worked. As soon as I submitted my application I got the confirmation email right away.