Bullfrogs are pretty easy to keep. Eventually you'll want a 40 breeder or larger. The biggest problem with them is that they spook easily, and with their powerful legs they can break their noses, knock the lid off the tank, or even kill themselves when they panic and try to leap away. So, provide lots of cover and make sure the tank lid is secure. Keeping the frog in an opaque or translucent container, such as a Sterilite or Rubbermaid bin, is safer.
I prefer to keep ranids in a mostly-land setup with a big bowl or pan of water that's easy to remove and clean. If you want more of a paludarium setup be sure to keep the water well-filtered and change it frequently. I use oak leaves and/or coconut fiber for the terrestrial substrate. Fake plants are great. If you want live plants, get big tough ones, because the frog will trample any small plants.
Bullfrogs will eat anything that moves and will fit into their mouths. Standard feeder inverts like nightcrawlers, crickets, roaches, and phoenix worms are good staples. Some people feed their frogs pinkies or fuzzies, but I don't see any real point to this; the pinkies are too fatty to be a good diet and are too expensive for my taste. Bullfrogs will also feed in the water, so you can use feeder fish or shrimp. I prefer livebearers (guppies, mollies, platies) over cyprinids (goldfish, rosies, white clouds).
