Those would work, however, I like something a bit deeper so that the fins don't drag too much since this can make them tatter-at least 5-7 inch tall containers is what I like to use....
To heat-you can use a large tub of water with a heater and set each cupped Betta in it......you also need to make sure they can't see each other all the time-its good for them to see each other for a short time a couple of times a day-but not all the time......I usually grow my males out in 76-78F water temps.
And yes, 100% daily water changes for cupped males growing out.
Also, good nutrition is really important-good quality varied diet in small frequent meals.
You want to get good body growth before the fins....