Mystery Snail and ADF Qs

African dwarf clawed frogs don't get very large, so should be fine in a ten gallon. Adding a couple fish should also be fine, as long as fish are at least as large as the frogs, and relatively fast when need be. I have full sized clawed frogs, and they eat fish up to 3 inches long, any they can catch. When you turn off your aquarium light at night, many types of fish settle to the bottom, making the easy frog snacks. Mollies, swords, platies, etc would all be fine additions, but all are live-bearers, so you would need a nursery tank if you don't want the babies eaten by the frog. As far as feeding, I would go with a high-quality flake for the fish, and sinking pellets for the frogs, supplimented by a quarter cube of frozen bloodworms or tubifex a couple times per week.

I semi agree with SherLar. A 10 would be too small for a mollie or a swordtail, but 2 platies would be OK. You can have either 2 males or 2 females to not have any baby issues. Most livebearer babies hang out on the surface anyway--out of the way of ADFs.
PS--Plants are nice, but not really needed.

I would definitely say "No" to a betta with an ADF. I tried it, it didnt work. They would fight over food and the frog was constantly going after the betta and trying to eat its tail. In my experience, a frog, even the tiny ADFs, will try to eat anything that it can catch that it thinks will fit in its mouth. Full sized platies should be fine though. I cant see the frogs trying to take them on. Just make sure you have another option if the frogs get adventurous.