Currency in Myanmar is Burmese kyat.
Here is a price list in Myanmar for reference (by 2015):
A bottle of water (500ml): US$ 0.35
A local beer at a bar/restaurants: US$ 1.2
A glass of coca cola in a restaurant: US$ 0.9
Street food: US$2.5
Western decent meal at local restaurant: US$18
Cash (in USD) works in most travel destinations of Myanmar although Kyat is more favorable.
International ATMs are available in tourism towns, which dispense Burmese kyat only. You may please contact your bank for detail instructions of daily withdrawals limit and charges. Small notes will be very useful for tipping and local street shopping. If you are going to bring cash to Myanmar, please make sure notes are in pristine condition with no defects, or they will likely be rejected as counterfeit. Get the most recently dated notes you can as these stand the highest chance of being accepted.
Credit and debit cards can be used in many shops, hotels and decent restaurants in tourist destinations.
As to tour cost, you may compare