It's not setup for anything. There aren't many countries in the world where you can just decide to go be there without a visa for as long as you want. Thailand is one of those that you can't do it. If you want to abuse the system then you can pay illegal bribes. That's a decision you can make, but the system isn't setup to cause that.
There is a very clear system setup for you to have a long-term visa. It's not Thailand's fault that you can't meet those requirements.
it shows you're not a tourist. That is why they are denying entry to people. Visa exempt is for tourists and someone trying to live in Thailand is not a tourist. That's the entire job of an immigration officer
that depends on if you get a visa before you travel or not. If not then legally you're required to have proof of a ticket out of Thailand within 60 days. Immigration almost never checks but you might have problems with your airline.
If you get it the visa first then it's not a requirement.
You'll look for this option for the 90 day non-O visa.
Make sure after you upload your passport front page and the system autofills your information, check very very carefully. Many people have had their applications rejected because the autofills system put an incorrect O (letter) in the passport number instead of 0 (zero)