G'day m.punga,
You've definitely got a challenge on your hands! First of all, a lot of elapid species, especially live-bearers will shed their skin within 24 hours of being born. I'm guessing you missed all the tiny little shed skins amongst all the afterbirth and gunk that comes with live-bearing snakes.
If they haven't had a feed in a month, you need to get on top of them straight away. Once they lose condition, it is near impossible to get them to put it back on. Another thing is, don't get attached to them. Even the best elapid keepers lose a few juveniles, especially Tigers and Copperheads.
I'm not sure what your elapid experience is, but by the questions you are asking I'm going to assume that keeping them in captivity is a new venture for you. First of all, make sure they are seperated into individual enclosures, as they will definitely eat each other. They won't need heating, as long as day time ambient temperature is around 26 or higher. The first method of feeding I would try is small fish, which you can get from a pet store for pocket change per scoop. Dangle the fish in front of them using a set of forceps. They won't immediately grab it like an adult Tiger will, so keep it in front of their nose and let it wiggle about. Normally they will raise their head up, and you'll see their tongue will be darting in and out quite rapidly. When they do that, stand real still, because after a few seconds they usually nuzzle up to it and slowly open their mouth and clamp down on it. Almost all of them should take fish - after a few feeds of it, try feeding them on washed pink mice, covered in fish slime. They will normally take it.
If the fish thing doesn't work, send me a PM and I'll give you some other methods.
Hope this helps,
Jonno