Not worth buying lots of Beer Lao just to save 20+ Baht a bottle. Buy something to bring back that you can't find in Thailand, such as Somersby Ciders (incidentally, also brewed under license by Beer Lao).
It's 59 Baht at Tops for the normal Beer Lao and 68-70 for the other varieties. Naturally it will be more expensive than in Laos as it has to be transported here and distributed.
Employer based ones are good. If you're not working in Thailand, there are several big name ones you could look at. Search "expat insurance Thailand" for options. AIG, Allianz etc would probably offer something but they may not be the best in terms of price or coverage.
Anonymous participant You can. He means you can't settle in Thailand on a DTV. You can only spend 6 months per entry, or 180 + 180 days if you're able to get it extended.
No. For medical services, you don't get any privileges over and above what a tourist gets, while on a DTV. At many public hospitals, Thais pay less than foreigners. At some of them there is a 3 or 4 tier pricing system. While on a DTV, you'll pay the highest price out of these tiers (work permit holders pay less, while migrants from neighboring countries pay even less and Thais pay the least).
At private hospitals, in theory at least, everyone pays the same but it's recommended you're insured.
Not just that, but most banks will charge you a withdrawal fee on their end (AUD / CHF / USD/ EUR 5) usually and a percentage charge of up to 3-3.5% of the amount withdrawn.
Only a small handful of banks refund these charges.
Thus withdrawing money from a Thai ATM can be very costly using a foreign card.