I have had one delay /missed connection in 10 years with Quatar airlines in Doha - You are scare mongering I think.International air travel is very easy ( But like Life not perfect)
I think I see why you want to go that way My experience of going to Thailand for 10 years is that Netflights are good -They were owned by Thomas Cook /Now a Dubai invest company . I have found the company pretty good , Hence returning to them with my custom .So there are good alternative choices out there .
I do agree, I get a small amount at my local bureau de change in the UK , I then use Superich in Bangkok . My last visit in September /October there rate was 43.5?
May I suggest that you travel very light ? If you use the Vans /Toyota minibuses there is not much luggage space anyway. Clothing in Thailand is very cheap reasonable . There is also street washing machines you can use to clean your clothes . Also Hotels /Hostels probably have washing facilitys ?One must is to have a good hat to protect against the Sun .Just shout if you need any more advice .
Cash ? Do your research before you have the treatment . This happened to me in Northern Thailand . I suspect that in Bangkok it might be easier?Just be aware of the issue .
I had some excellent treatment at Mahidol University in Bangkok . I believe this is also a Teaching Dental School .The process to clerk me took a while . But the treatment was Root Canal work which relieved my pain . The cost was reasonable .Be warned -I have found out that a lot of Dental Clinics do not take Foreign Credit /Debit cards .