1.
Bagan (the whole place). Not sure how comfortable you are driving an electric motorbike, so you may want to look into transportation around Bagan. I can get you a contact if you need.
Schwedagon Pagoda in Yangon.
Mahamuni Pagoda in Mandalay. Mandalay Hill is a can't miss. U Bein bridge is also pretty popular.

2.
I did not use a travel agency, did it all myself. Used taxis and cars for hire. Taxis ran $2-$6 except in Bagan where we got ripped off and were charged $11. We did hire a van one day, drove maybe 100 miles total, and we paid $35

3.
Yes, they have food there. I mostly only eat local, so I spent $2-$8 per meal. Coca Cola is around 40 cents, beers around 80 cents to a dollar.

4.
My hotels usually included breakfast in the morning. Hotels are about the most expensive thing in Myanmar, with souvenirs, food and drinks being pretty cheap. You can now book bus tickets online, which was helpful. You can take an overnight bus to Bagan from Yangon and see the sunrise.
I do recommend to people to fly into one city and fly out from the other, so I like that you plan for that. Be aware that if you fly to Bangkok, AirAsia will be at a different airport from Delta/Korean/China Eastern. AirAsia will charge you extra for your luggage, so I like to take Bangkok Airways. Why cant you route into Yangon via Korean Air?
I do not recommend people depend on ATMs or credit cards. People will say they had no trouble by using ATMs, but make sure you keep a couple hundred US dollars with you, brand new notes.

Do note, that I converted the prices to dollars just for ease of budgeting. Everything was paid in kyat.

10-14 days is great. You can see a lot. I'm sure you'll get a ton of advice here.