They do not need a very wet environment, but they do need to be misted frequently.
Neoregalia bromeliads have a great variety and a wide availability. There are many bromeliad farms in the states you could order from. The Canadian Dart Frog Society just did a group order and it worked out to 4$ for each bromeliad after we ordered 50+, of course some of the rarer species can run 20-60$
They are not toxic, to my knowledge, but there may be some that are? I doubt it though (there are many many many species however).
They don't have very strong root systems, so they will need to be secured into your cage with wires, glue, or some makeshift hanging method.
They should never be planted in the ground, as they are meant to live epiphytically, which means they get their nutrients from the air and humidity and with spraying. You should mount them from the middle of your cage upwards.
They like lots of light, though there are many species you can get that do well in low lighting levels.
They would be great in a veiled chameleon vivarium, but they do need to be secured well so the chameleon doesn't make the plant fall off the wall/background when they crawl on it.
There are some varieties that grow very large, and those are the ones I would recommend using for chameleons.
As for coming from their natural environment, no they are found in the Americas.