For those who cannot read, it is an EXO TERRA TERRARIUM not a glass aquarium. These can be used with smaller species anywhere in the world. You can use them in the middle of the desert if you had a house there that you kept cool with an AC. So many factors play into whether or not its a good cage to use. If you want to be able to take the cham outside for natural sun I suggest a screen cage so its easy to move the whole cage outside.
The exo terra is too small for adults of larger species. You can use it for babies to maybe sub adults for a panther or veiled but once they are full adult they will need a larger cage. A jacksonii would probably be alright, although, WC specimen should have plenty of room to make acclimation easier. You could always use the exo for a baby and juvinile and switch them to a larger cage when needed and use the exo for some frogs or something else.
Ditch the waterfall. Its been said 100 times. Even if it wouldnt cause a problem for the cham bacteria wise it would simply take up too much room in the enclosure.
I would not suggest housing jacksonii together. The main reason is stress indicators are sometimes very subtle and someone getting into chams may not be able to see these indicators. Also males will try to constantly breed with females and stress them out until they die. It might be possible to house a few females together but you would need a much larger cage. It also depends on individual specimen. One may be more aggressive than another.
When using the exo terra you will not want to soak it with the misting system because of the lack of drainage. Read this article for more information on using an exo terra correctly for a chameleon.
http://chameleonnews.com/10JulAndersonGlass.html
Here is also a good article on jacksonii.
http://chameleonnews.com/10JulManchen.html
Any specific questions feel free to ask. Hope this helps.
Edit: If you are going for a jacksonii you want to find a nice well started captive bred specimen 4 plus months at least. Babies of this species can be trickier than other species so you want a well started one. If you decide on a WC be warned that they are not fun. I would go to a show and pick it out so you know you are getting one in decent shape. Exporters will ship whatever. Its just luck of the draw if you let them pick it out. Do some more research on acclimation if you are going to go with a WC. I dont suggest it for a beginner but starting out with spot on husbandry and a good specimen a beginner can even do well with a WC.