Myanmar is a newly open country and it would be difficult for anyone to give you a turn key solution, even there are some consulting companies that have a good knowledge of the country and can help you. But since you are willing to open a coffee shop or something similar, it might an expensive fee for you to go through a consulting cabinet.
For me, as you are planning to stay there for 6 months to start and see if you enjoy life in Myanmar, the cheapest solution and probably the one which can give you the best ideas, is just to try to be part of the city, wander around, check what's existing and talk with people, and I am sure that you will come up with a lot of great ideas, since there are many things to be done in Myanmar and endless opportunities as in every opening country with good potential.
You might need some advice from a consulting company, or a business lawyer to help you with the paper work and to apprehend the regulations, but they will not find ideas for you.
As for the free wifi connection coffee shop, it can be a good idea, but there already are such type of shops, and you need to be sure that you have a strong connection, Myanmar internet being quite unstable.
Maybe you want to come up with a shop or business that Yangon is lacking, directed towards expats or locals, but you will see for yourself what's best, I don't know what are your aspirations.
It might be common sense what I am saying, but I hope this still helps , Chok Dee !!