The marriage visa there is alot of extra paperwork involved ok it's 400,000 in a Thai bank that is required the retirement visa is 800,000 Baht in a Thai bank but alot less paper work.
If you can afford it I would go the retirement visa as you are more independent on that visa which ever you decide you will also need a multi re entry visa that is 3,800 Baht and you can go in and out as many times as you won't while your yearly visa is valid
Yes and the question will be asked are you still on a holiday if not get the correct visa to be here in Thailand the entry Thailand was not a visa it's permission to stay in Thailand for 60 days and then can add 30 days by paying 1,900 Baht after that you need a VIsa to stay
been here many years own business here and my understanding is a foreigner can't own the land in his or her name the actual house yes with a company set up yes but the company can't be set up just to buy a house and land as it's not legal