If you're doing a 10 gallon enclosure, you should only have one frog in there. Max size for these frogs is about 2.5 inches, with males being smaller. I have a male gray tree frog that is actually only 1 1/4 inches and doesnt appear to be growing anymore. Males CAN live together if you were to put them in a 20 gallon instead of a 10.
The pond should be shallow enough that he wont drown (no deeper than his head) Definitely concentrate on the arboreal aspect of the tank though, that's the most important part for a tree frog.
And you're welcome, we're all happy to help!