Ah, you are from down under! Yes you are correct, the rest of the world calls them White's or Dumpy's to you guys, since they are natives, they're just plain old green tree frogs.
Well like I said, the rule of thumb for White's is 20 first frog 10 each additional, so for those two you would need a 30 gal tank. It sounds like you have an exoterra style tank (doors in front). You can try on the other site I frequent, repticzone, in their tree frog forum there are loads of White's owners. Also in their members area there is a converter to tell you how many gals your tank is based on the measurements.
They can't be in with any other frogs, they will get huge and will eat other frogs, including their own kind if they are more than 1/2" difference in size. Two or more of the same size can be together as long as space is adequate, there are enough hides and food.
They also need a water dish to soak in, they also like to eliminate in their dishes too so it really needs to be changed out everyday, with treated water.
They are eaters, they get to be about 4" snout to vent. One of the biggest, but they are super cool and seem to really have personalities. I have red-eyes and they are beautiful when they are awake and moving, but that is only a few minutes a day, then they are just blobs on the pothos.
Pothos will work well, you will need strong leafed plants to hold them, check with some of the other owners about what they're using. Also most of them feed outside of the tank to avoid impaction since they eat the crickets and anything else that comes with them into their mouths.
I'm seriously considering getting some white's for my new tank, they seem like they will be more interesting than the red eyes are.