Ok, so, while the silicone is curing, I have a few questions regarding how I'm going to set up the terrarium. I've included pictures, but, keep in mind that none of the wood in there is what's going to be in the final one. It's just there for reference, to see how much ground space will be left if I use pieces of similar size. I'm thinking of putting a fairly thick branch or piece of small trunk in at least one of the corners, from bottom to top (or almost), to act a little bit as tree trunk. I'll also try to find a medium size branch with smaller branches, to provide perches. I'll put in some pothoses and maybe I'll stick a few fake plants on the sides. I'm also thinking about putting some pieces of moss or fake moss bedding at the bottom (and maybe hang some from the branches).

I'll look at what's available backing-wise at my pet store, but for the moment I'll probably just go with a green piece of cardboard stuck to the back of the terrarium (outside).

There may end up being two plant pots, but the soil will be almost level with them, so they shouldn't take too much away from the ground space.

The glass bowl will be the water bowl.

I'm trying to do something that will look good and be good for the frog, but I have a very limited budget (which explains some of the questions below), and I'm trying to do something that will provide the frog some privacy, while being easy to clean and making it easy to remove the frog from there when I need to.

Here are my questions:

Do gray tree frogs need any ground space (and how much of it)?
I have aquarium gravel, which I could put in the water bowl. Is there a chance it might accidentally swallow some even though (I'm assuming) it won't be feeding in there?
My preferred option for the water bowl would be to use pebbles instead, but do I need to buy the (expensive) aquarium-safe pebbles found in pet stores or am I ok with the decorative pebbles found at dollar stores, hardware stores / gardening centers, etc.?
Do you guys have any tips to add perches/mini balconies to the terrarium's side?