I cannot answer your first question. I can state that IMO the pass program from Thai Airlines is not worthless. It is cheaper to fly individual tickets than the pass with some minor exceptions. The 1X CNX-HKT non-stop is the only one that I know of. The cheapest run is the 4X/day Chiang Mai - Mae Hong Son run on an ATR-72. The problem with this run is that it can only be done 4 RTs per day per the optimum schedule, it is all the same plane and Mae Hong Son at certain times of the year, has fog and forest fire smoke problems that close the airport. So if the airport is closed, you do not fly. It is quite cheap, last year approximately $18/segment. I do not not know if you get actual miles, but I assume that you do not, then you will have to qualify on segments. You can do the math, two segments RT BKK-CNX and 8 segments per day. So it will take a week or so to do this on segments. Even if you got 500 miles per segment, in order to get 100k miles, you would have to do 200 segments or 25 days worth of back and forths without any mechanical or weather delays/cancellations. This equates to 24 nights in a Chiang Mai hotel and hotels, for the most part, are not quite as cheap as Bangkok. Guest houses certainly are, but 24 straight nights in a guest house in Chiang Mai might be a stretch. And then, if you are not staying in a hotel which offers airport transport for free, it will require paying for a van pickup or songtao.