fire eels are very sensitive when small so make sure you have a test kit on hand to test your water frequently, do regular large water changes, as for food ime live blackworms are the best foods for small spiney juvies in general. My fire eels have never bothered tank-mates even if they could easily swallow them ( example my current 12"+ juvi lives with among other community fish a school of glow-light tetras and could easily eat them but doesn't) any small meaty food ime of the invertebrate nature is usually welcomed by these fish and they can be extreamley finicky/picky eaters so having a variety of foods is key and encourageing them to eat as wide a variety is also healthy for them. He will also probably hide the first few weeks or even monthes... let him. Once they settle in and are aware food comes from you it will come out whenever it sees you and likely pester you for food anytime it sees you! a very smart fish that is often reluctant, but not always. can't force any animal to "like" you but I found bribs work wonders for bringing spineys out and about.
If they are stressed/scared, exposed to aggressive tankmates, poor water quality... they can and will jump out of tanks easily even the best covered one. The best thing to do is not give them a reason to escape, because if they want too they will eventually accomplish this.