this is what my agent send me as a message. Sounds plausable. Be aware :
The automatic visa extension is for tourists wishing to stay until JULY 31. Once the airport opens up again those under this extension they MAY have to leave, and when they wish to come back they MAY have to get a visa from the Thai Consulate, and MIGHT also have Covid19 health insurance.
Please share our contact information if you know anyone that needs LONG TERM visa services. Immigration is still open for these services.
"I have a teaching job now in Bangkok (planning to start 20th April)." Are you 100% sure this job will still exist in 2 -3 weeks when things get even worse ? I would prepare to the fact the school will cancel your job due to the Corona circumstances
If you will stay here much longer, i advice you ro contact Aetna, to get at least a healthcost insurance. Normally you will get it for one year. But surely there are also SA insurance companies that do every thing online?