since you are married to Thai you can still get non-o based on marriage to get 90 days on entry but for the extension need to have 400k in bank 2-3 months prior. But since you gonna be under, I would look into agents.
No and no. For non-o based on marriage you need 400k for non-o based on retirement you need 800k. Sure you can maybe use agents if you have the funds for that.
If you don't have an extended history going out and the county you will not have any issues coming back. But if you that scared get a non-o based on retirement gives you 90 days on arrival that you can extend 1 year if you want.
You can yes, but many reports at immigration hassle you to get a real visa since looking at you trying to live there on visa extempt / tourist visa entries.