Just my 2¢ for this project, I'd say that this is definitely not suitable for dart frogs. While they can certainly be kept in a 10 gallon with plenty of space (variables depending) and should have no trouble in a paludarium-style setup, I feel that your individual tank layout could not support any dart frog healthily. it looks like 1/2 of the volume is taken up by water, so that leaves you with a five gallon tank, and of that five gallons (species depending) less than half would be usable by terrestrial frogs. Darts need large amounts of leaf litter to keep them happy, and I can't see that working in this setup, as most of the leaves would probably just fall in the water and there's hardly a space wider than an inch or two's width (I'm not sure what's going on in the back corner). I can't be sure, but it appears that your soil is sodden with water, and therefore would not be able to support the necessary microfauna (springtails, dwarf isopods, nematodes etc) that are needed to stabilize the ecosystem and provide additional foraging items for the frogs. There's simply not enough solid land here to be able to support them. Any of the arboreal species would not work in the setup either; assuming you filled up the entire empty space with broad-leaved plants and such to provide the maximum amount of living space, they would still have about six inches of height at most to move around in; in a 10 gallon, what I consider the smallest acceptable tank for any dart frog, arboreals need a vertically oriented tank so they get the most out of the 18 inches height possible for climbing. most darts also do better in groups, which you would not be able to provide here.
as for alternate stocking ideas, this setup looks perfect for a fire-bellied toad. You can still plant it up as you had planned and it will love you for that, but it will actually utilize the water section as much as the land section. No fruit fly culturing to worry about here; they eat the standard crickets, mealworms, anythingthatmoves etc. that's the best species I can suggest that will go on land and use the water as it is; if that's not an issue, you could go for spotted floating frogs, which will stay almost exclusively floating on the top of the water (I have a couple of these guys just in my tank- they're awesome!
or some smaller species of newt, say paddle-tailed, fire-bellied etc, though for those you'll want to watch the water temperature and at least place a layer of sand over your substrate to avoid impaction of the gravel.
Aside from that, this looks like a promising start. As for plants, many of the aquatic plants we know and love grow quite well emersed; ludwigia, hygrophila, bacopa, anubias, etc and won't have a problem with wet soil. The vast majority of stem plants take to emersed setup quite well, as long as they are transitioned properly and kept humid. You should really consider Microsorum species (java fern)- they take a bit longer to acclimate and need higher humidity to do so, but they work quite magnificently once they've been transitioned. HC makes a great carpeting plant and takes low light well enough emersed; riccia is also another good option, as well as most aquarium mosses (all but java and willow moss aren't fully aquatic). you should definitely get some Selaginella and creeping fig for the background (variety 'fig leaf' looks better imo); good sources for vivarium plants can be found here http://www.blackjungleterrariumsuppl...lants_c_1.html
and here http://www.joshsfrogs.com/live-terrarium-plants-1.html
, although many of these plants will have issues growing in your setup if the soil stays as wet as it appears to be.
good luck, hope this helps.