Hi Thanh,
If you are coming to Yangon. There are a lot of hotel in Yangon now, a lot of them are new and not so expensive. Google-ing "cheap hotels in yangon" might be helpful, and depends on what is your purpose of coming, location of hotel might be crucial, since traffic jam is pretty bad here.
It will be good if you bring some medicine for digestion if it is your first time here.
For food you can visit this website: a lot of review for Yangon restaurants.
One important thing: you have to bargain with the taxi driver in Yangon!