Congrats on your purchase RETF's are one of my favorite frogs....I'm currently housing 2 in an 18X12X12 exo terra with live moss, pothos, and some sort of grass I picked up at home depot.....One would be fine in a Ten gallon. The main things with these guys is humidity, cleanliness, an appropriate sized water dish, and a really good substrate. They're extremely messy eaters, and will often injest some substrate along with their cricket (I've lost a few to choking in substrate while eating In my early frog keeping days)...So on that note, I would suggest either live moss, or paper towel if you don't mind the un-natural look. Its cheap, extremely easy to clean, and fool proof. No gravel, no bark, no loose substrate for these guys.
As far as humidity goes, I mist them once or twice a day, and offer a water dish with about 1-1.5 inches of water. They will often sit on the edge of the water dish at night with their butts submerged to rehydrate.(extremely cute I must tell you) I also have a rock in the middle of the water dish to prevent drowning. (They're decent swimmers, but accidents happen.) Plants will also help hold the humidity. If you're working with a screen top, I suggest covering 2/3ds of it with saran wrap. If you hold a hair dryer to the saran wrap covered top, it will sort of meld to the screen and become more semi permanent. Wierd I know, but its worked for me in the past.
As far as plants go, it depends on what you like. Pothos is a favorite of mine just because its so undemanding and has really nice sized leaves (and there are also many different colors/types to choose from) bromeliads are pretty but require more light. I've used Fittonia Red Vein in the past and it was undemanding and functional for the frogs. They're going to like large sturdy leaves they can stick to (no fuzzy leaves)
I get all of my terrarium plants from home depot, rise them really well before planting, and I've never had any problems with any of the Exotic Angel plants I've tried..... at this point I'm pretty sure I've tried almost everything my little home depot offers.