I have tried many plants in my indoor setups over the years and have found schefflera (arbicola) to survive the longest and provide many horizontal branches, and ficus "alii" in the tree form to do very well and survive for years. For the amount to use, make it comfortable for the chams by giving plenty of hiding places but don't overcroud them so much that they can't move freely. Make sure that they can get close to a basking source on one plant and away from it on another.