@Tod ********
Thank you so much for your detailed answer. So I understand entering on visa exempt is possible. I was scared a bit, as I read that visa exempt is for tourismn purposes only. And when immigration sees that I loved in Thailand for the past 2.5 years and just was out of country 10 days to Vietnam, that they will not approve visa exempt to me.
With regards to all the other questions, I anyway will have to see Mukdahan Immigration in March for my next 90-day-reporting and will ask them in person then. Just wanted to be prepared best possibly.