Flight from Bangkok to Yangoon

Yes... "trustable"... AirAsia is a budget airline, along the lines of Southwest Airlines and Easy Jet.
No frills.. fairly reliable. This is an early morning flight, and generally on time. Other routes later in the day at times have some "schedule issues".. meaning.. not always on time.. Certainly the cheapest on the Yangon/Bangkok route. Checked in luggage free limit is 15 Kg. (you pay a penalty for overweight). Generally the longer time before the flight you book.. the less you pay. Currently they fly Mon, Wed and Fridays...
Alternative airlines.... Thai Airways and Bangkok Airways.

I used Air Asia three times recently including Yangon-BKK. Two flights were on time and the third left 30 minutes early. And as noted in #1, the fact that it's an early morning flight means it's more likely to be on time. I think Air Asia is great.

Yes I totally agree.We had return flights in June /July and both flights were great.

Air Asia has a 15KG total checked bag weight limit.

Air Asia is fine.