1.) They can live with a variety of different species of fish. Pretty much any peaceful community species that don't have super long flowy fins! I have a otocinclus catfish, a dwarf gourami, and a Dalmatian lyretail Molly, and 2 red minor tetra with my 3 ADFs & they all get along great!
Through research when I got my ADFs I've learned that the following fish are compatible tank mates for ADFs: guppies, mollies, plates, dwarf gourami, corydoras, danios, tetras, shrimp (I think most any species is fine, but everything I've read tends to emphasize cherry, ghost, & bamboo), mystery snails, and bettas (females are recommended because they tend to be less aggressive & don't have as long of fins).
It is recommended that you don't put Cichlids or kohl loaches with them.
2.) I have a ~2.5" gap on my lid, where my hanging filter was before I got my sponge filters, & haven't had any issues with them escaping. Although, every time one is hiding from me in the tank I temporarily freak out thinking it escaped LOL!
3.) I've had 3 ghost shrimp & a mystery snail with my ADFs & while they all lasted a few months, the frogs did end up eating the shrimp eventually! I had bought them specifically for that purpose when I went out of town & was worried about my froggies starving, but they didn't eat them on that trip & I really grew to love those cute little ghost shrimp more & more.. like at the same rate they grew lol! 2 of the 3 got literally as big as an
adf so I'm still baffled that they were able to eat them!! I was not there to witness it though.
Everything you will read will say that ADFs won't eat snails. I guess I'm one of the few unfortunate ones bc I got back to my office one Monday morning & there was a empty snail shell in my tank with literally no trace of the gastropod ever existing!! I don't know if it died on its own & then the little fatties ate it, or if they went after Gary while he was alive..
4.) I have found my little community to be fairly easy to take care of. People had me worried that maintaining water conditions in a 15 gallon tank would be be difficult, but I haven't had any issues at all. I use the API 6-in-1 test strips to test the water before & after water changes.
Make sure your tank is cycled before you purchase your frogs. I have a corner dish {like one for a reptile tank..you can see it in the attached pic} that I feed them in. They come RIGHT to it when I drop the frozen brine shrimp in to feed them! I have gravel substrate & was worried about them eating it so that's why I got the dish & also feed them with a turkey baster. Little suckers are more blind than I was before I got Lasik!!
Hope this info was helpful & you enjoy your new little goofballs!