Hi timur--
1. The passport photos we had taken were 2 x 2" but I cut them down to fit the dimensions on the visa application which said they had to be 35 x 45 mm.
We're going with a group tour and that company emailed us in August to tell us there were changes in the visa application process. They said that 3 photos are now required. I was unable to verify that on the Myanmar embassy website and the newest visa application which you find there (updated August 2012) only says to include 2 photos. BUT, in an abundance of caution I sent three. It was annoying to spend the extra $5 each for one more little photo but I didn't want to take any chances.
Another change that tour group mentioned was "should you reside in New York, New Jersey, or Connecticut, you will require a different visa application." Looks like that doesn't apply to you but in case anyone else is reading this....
2. We included a copy of our air itinerary but not copies of actual tickets. We also included a printout of the tour itinerary showing daily activity and what hotels we'd be staying in along the way. I attached a duplicate to each visa application, not just one for both of us. Again, maybe overkill but I just didn't want to give any reason to have the visa apps denied.
3. I sent both applications together in one FedEx package (the bigger tyvek envelope) and inside I also included a FedEx cardboard envelope for them to return them to us which had a completed label with my FedEx account # and address filled in. I just included one for them to return both passports together.
And the $40 money order made out to Myanmar Embassy.
After overthinking that I'm now on to overthinking getting prisitne $100 bills. Not easy! Let me know if you figure out a good way to do that. Most banks are telling us they don't get new bills in and we just have to take the best they have.