No need to give them a pond. They are not fish. They do like water though so you may offer them a pond if you like. I just use large mortar mixing tubs. Even one of those large plastic ponds is not going to allow room to swim for an adult anyways. If I want to see them swim I let them out to the pool.
They can be very tolerant but its not a given. You could end up with a beast that hates you just the same as them liking you.
As for food they will eat almost anything after all they are monitors. Mice, Rats, rabbits, chicks, chickens, piglets, fish, insects, etc.
Cage size as big as you can give them. Don't try stuffing a large one in a fish tank. haha My larger ones are currently housed in 8 x 6 x 3 cages. They are outgrowing them and will need to be moved into larger cages yet. So go big if you want to go home with one of these.
