He's not getting con (TVC) own this group. You can see their details on the banner above. They are legit agent, but you are correct that OP doesn't need that. But if he is last minute and doesn't want to bounce then he has to use them.
OP is confusing getting married with getting a marriage extension. You nearly have the OK to get married. Getting a Non-O then a yearly extension based on marriage is completely different from getting married. Getting married is the requirement to apply for the Non-O, it does not give you the visa right away. You are way too late to apply for everything unless you use an agent or bounce. As others have said, just do a border bounce and come back to us when you get your marriage certificate for more advice. It take 1 hour to get married, not 3-4 weeks. The process at the district office should not be weeks, I think you are confusing a lot of things therefore we can't advice you well.
Illegal in the sense that you cannot work in Thailand without a work permit or LTR. So you cant come here on visa exempt or tourist visa and work online until you get work visa or LTR. This is illegal. BUT... this is rarely enforced. Unless you talk about it online, nobody will know nor care about what you do at your house or in a random coffee shop.
"I run and will continue to run a ltd business in the UK and that's where the money will come from to live in thailand.". This is ILLEGAL but NOT ENFORCED. Which mean that you can still run your business online while in Thailand, but avoid making post like these where you tell the world about it! :)
On the basis of not having the funds to support yourself? The 3 proof of exist no matter the visa you are in. Im not saying its great, but some border care about it.
You misunderstood what he said. He said that with multiple entry it's a gamble whether or not they will ask for the proofs. But, in your situation, they will. You had the 3 proofs therefore there was no gamble.
Exactly! And we can assume that either she used an agent, or the school did. Most likely also the agent/school will ship passport back after under consideration is over. It seem pretty obv to me.