You'll definitely have better luck getting all of your questions answered if you break them up into the appropriate forums = ) I know it can be confusing if you are new to using forums. Because we are in the feeder forum, your questions regarding specific husbandry about Fire-Bellied Toads will likely be overlooked as we are banking on a fellow FBT owner to read through all of these posts and respond. Try posting FBT specific questions in the Bombina forum where plenty of FBT owners will be browsing the new topics eager to help you out in any way. Here is a link to the Fire Belly forum:
Fire Belly Toads (Bombina)
I do not actually keep FBT's... I'm just very familiar with feeder insects and insects in general so I primarily stay confined to this forum. Working in an entomology lab does that, lol ;P
So I'll try to address some of your questions from the previous postings regarding feeders:
The snails will likely be a no go. Snails and slugs have the capacity to act as feeders if you can ensure they are raised in captivity (and the snail's shells have been removed) but this isn't a very common practice to my knowledge. The issue is what they can get into in nature if you collect from the yard. It would not be difficult for either of them to get into some kind of nasty chemical -cide which would make them potentially toxic. Furthermore, gastropods like snails and slugs are notorious for being parasitized by a plethora of potential pathogens, so feeding them may introduce a parasitic pathogen to your frog.
Mealworms should indeed receive some sort of moisture source - apple slices, greens...virtually any kind of vegetable or fruit can work. Try to avoid fruits that are very moisture rich though, as too much moisture settling on the gutload/substrate that the mealworms are living in can result in bacteria and mold growth. Waxworms will not eat anything unique that you try to offer to them. In nature, they are specialists that feed on beeswax and derivatives and are a pest species to bee keepers.
All of your other questions regarding the FBT's specifically will likely be best addressed in the Fire Belly Forum I linked to at the beginning of the post = )