Welcome!!! American green tree frogs would be a great starter tree frog. They are pretty hardy. You could follow the same care instructions listed for grey tree frogs which can be found Here. I am not sure about breeding, but tank size, temps, humidity, foods and etc would all be pretty much the same.
A heat mat is not essential unless you get some crazy low temperatures in your house. I try not to ever let my grey tree frog tank fall below 65 degrees though and will put a heat mat on to warm it up if it seems to be chilly for a long period of time.
I would also recommend UV lighting even though many will say it isn't needed. We are not sure how it affects frogs but my frogs seem healthier with it. Also, if you're growing live plants in your tank (which you should definitely consider,) it's a must have in order to keep them alive.
Has anyone considered typing up and AGTF care sheet??