That question wasn't a joke. It's cultural sensitivity. If you want things to go smoothly in thai banks or the immigration office, dress like a business person. Especially, if your case is in a gray area.
I believe you are overthinking it. True, with the work gone, you might have issues extending. An agent might help you find the most benevolent immigration office and/or have already some experience with a case like yours.
If you want to be cheap, just go to the nearest immigration office and ask for yourself. Remember: you did nothing wrong and just want to keep enjoying Thailand. They should be supportive if you have funds.
Depends on how long you are planning to use the Visa. If you see yourself staying in Thailand for more than 4 years (on and off), then you are losing almost 1 year of visa fee by applying too early.
The DTV won't be cancelled. What might happen is that the soft power requirements will become more strict, but paying for 6 months of muay thai will likely still qualify you in 10 months from now. If you (as it seems) don't really like to do Muay Thai, now is still a good chance to get a DTV with way less expensive and shorter courses.
following. I will need that certificate and have received very confusing information. Some sources say that in Bangkok you only get the certificate after the first 90 day report, not earlier.
Some landlord told me no problem, but he has to go with me to immigration...
It seems to be a common theme with embassies/consulates in general these days, not specific to Thailand.
We have our flight to BKK already booked. I consider staying on the tourist visa first and then going to a nearby embassy for the DTV. Which one are you planning to go to?
Sounds like a smart choice. This e-visa has a scammy feel to it. My suspicion is that the consulates get to pocket the same amount of the fee no matter if they grant the visa or reject your application. Rejecting is less work for the same money, so the employees are tempted to reject.