read the law. It states this "The Immigration Act,B.E.2522,the foreigner who has received a temporary stay permit and stayed in the Kingdom of Thailand over 90 days must notify his/her residence to immigration officer every 90 days.". So, I don't know BOI and LTR - but they might not be considered temporary stay permits, but the DTV most definitely is a temporary stay permit since its a 180 day permit. Assume you need to do reporting because of this.
You can get a 12 month lease if you have the money. Some landlords will ask what you do and might ask for a work contract or proof of visa, but that hasn't happened to me.
Anonymous participant I haven't done it yet so I don't know how you can contact them. They have an email address, but you could try and go back and see if you can get an answer. I have not heard anyone waiting more than 2 days, in HCMC - they are very clear that it takes 2 days.
This sounds great but I would be careful about saying that you can make a freelance income. The individual on a DTV cannot work in Thailand and make money from Thai sources. Im assuming they wouldn't be making money from your facilities from a Thai company? If its making money under their own name they would need to make sure that the income is not coming from Thailand.