The frogs are actually quite big as adults, so you might want a bit bigger tank
The best food for frogs is anything live that moves. flies,moths,crickets, other bug, ect
Once they do morph, its best to have about 2/3 land to 1/3 water, also try to keep it well ventilated, and make sure there are no gaps in the lid at all, when they are little you would be surprised what they can fit though