- Tadpoles from the genus Rana generally don't eat a lot of animal matter. I would add a rabbit pellet or two to his tank and he should eat those.
- Tadpoles stop eating when they start to absorb their tail. A few days after metamorphosis (complete or near complete absorption of the tail) they will start eating tiny foods.
- Metamorphosing tadpoles are incredibly prone to drowning. I would remove him to a small tupperware container with a little island in water that is just barely deep enough to cover him - that way he can touch the bottom and breathe at the same time, or come out onto the island.
- Leopard frogs are more aquatic than many of the members of the Rana genus but frankly they are not an aquatic frog, and certainly not for the first 6 months or so post-metamorphosis.
- Leopards are known as big jumpers and they don't really make great pets because of their space requirements. The reason that mail order companies sell them is that they are incredibly common and used somewhat in science.
- Regarding an enclosure for the frog, when it is relatively small it won't be very aquatic (or not at all), so a completely terrestrial aquarium with no water is in order. It doesn't have to be very big (a 40 liter / 10 gallon would do for a metamorph) but as the frog gets bigger its space needs will grow dramatically.
- I wouldn't consider keeping a jumping frog like an adult Leopard in an enclosure any smaller than 45 cm wide by 120 cm long (18x~48 inches), and personally, I wouldn't keep one at all since they require so much space.
- The size of the water area for a large sub-adult or adult isn't important as long as there is one, so the size is up to you.
I hope I've been helpful.