Do mind that it has a bit of an expensive application fee but once issued there will be no need for extensions or reentry permits, which can add up. Good luck.
I've been using the METV for several years running, (typically for 5 month stays). It allows for 180 days with two mandatory exits after 60 days. If you actually plan a 6 month stay and take two exits to neighboring countries there'll be no issue with staying under the 180 day threshold if that's a concern.
Check the website "willmyphonework" Except for the most high-end phones, many phones are marketed to geographic regions and will offer frequencies and bands most frequently used in those regions. High-end phones offer a wider array of frequencies/bands that cover more geographic areas
The METV (Multiple Entry Tourist Visa) allows for a stay of 180 days and costs $200 USD. You are required to exit Thailand at the first and second 60 days but otherwise need never bother with a visit to immigration. Frankly you can exit/reenter as many times as you wish on this visa whether by air or land. Others will chime in with advice for how to stay for as long as 9 months on an METV. Your use case is similar to that of my wife and me and it's proven to be hassle-free and economical for us.
I'm curious where you're sourcing your information. To my knowledge the management team is made up of administrators from multiple countries of which the US is one. That would not be unusual for any institution seeking international credentials, investors and staff. That there is a McDonald's on the premises indicates nothing. That restaurant is a locally-owned franchise as are all McDonald's in Thailand. I hope you wouldn't suggest that by their presence in the county that Thailand is "owned" by the US.
Perhaps be a bit more careful with your "facts". Bangkok Dusit Medical Services, the owner of Bumrungrad 1 Hospital, is Thailand's largest private healthcare group. It was founded by the Thai billionaire Prasert Prasarttong-Osoth.
You're not the first to assume that my given name has anything to do with what I do or do not believe. Aside from that intended slight, references to health insurance from expats have nothing to do with the worthiness of travel insurance for travelers. And no one would argue that there are cheaper alternatives to private hospitals in Thailand, but as I noted many, if not most travelers would not be aware of those differences nor might they be in a condition to have a say in the matter.