For a 1 gallon I would recommend for you to have minimal substrate and float all your plants.
Heating shouldn't be a problem. the usual 25w heater with an adjustable knob. fits well in a 1 gallon, be it a bowl or a tank. I have heated half gallons with 25w adjustable heaters, so it really isn't a problem.
Always test your heaters first with a reliable thermometer.
Many stem plants do great floating. guppy grass is one of my personal favorites.
Water changes should not be a problem either. I've never seen traces of nitrates nitrite or ammonia in a healthy, well planted tank. especially since a betta's bioload is quite negligible. I do recommend that you start up the tank for a week or two before putting fish in to allow the plants to settle and adjust.
Plants will need lighting, a desklamp with a 6500k cfl will be perfect.