In an effort to keep up with the latest business news coming out of Myanmar, on my last trip I picked up an extra Myanmar Customs Declaration Form in the Yangon International Airport.
Customs procedures are straight forward, simply pass your bag through the X-Ray scanner at the exit and you are through in a couple of minutes.
Banks to change money are immediately outside the gates as you leave the customs check area. Rates inside baggage claim are approximately the same as outside in the arrival hall.