I have never kept them myself so don't know too much about them.
The name Green frog is wrong though they are Southern Bell frogs or Golden Bell frogs Green frog is another species so if you search Southern Bell frog or Golden Bell frog you will probably get more info on them.
As far as I know Litoria Raniformis are active during the day and night like Litoria Aurea.
I bought my frogs as tadpoles from the shop, but the further north you go the likelihood of finding the frogs in the wild increases.
If you got to a pet shop ask them if they know what the species of tadpole is as I was sold whistling tree frog tadpoles which turned out to be Green and Golden Bell frog tadpoles.