the only thing that I would think they'd be able to eat would be fruit flies. Try Josh'sfrogs.com. Or pin heads.
This would have been a good thing to think about before they hatched, no? I think a good deal will attack each other. That's just something someone told me though, not from research or personal experience.
They will molt fairly quickly at first. You should try and separate them into single deli cups with some climbing items (sticks and leaves) and spray the side of the enclosure when its dry to keep humidity decent for molting, but mostly for drinking (they drink dew). Dont make it wet in there. you'd be asking for infection and poor health.
Mantidforum is a much better place to look for advice.