Hi,
accommodation is really expensive in Yangon, thus ask for the budget that will be allocated to it. 3000/4000 should do it if you are alone, add 1000/1500 if you are coming with your family.
For medical insurance, make sure you are also covered in Thailand as there is no good hospital in Yangon. For anything serious, you will have to go to Bangkok.
As for the tax, it is still not very clear :
- Be just aware that there is no tax agreement with other countries, so just ask in your home country how they will consider your salary paid and taxed in Myanmar
- negotiate a net net salary, leaving on your company to pay any taxes that is due, be it corporate or personal taxes.
Cheers
Julien