I think the most believable notion is that the bodies are just templates to piss off or horrify the people and that teh ring itself is the main power house. That would explain why they only die when the ring is destroyed, it's whats keeping them strong and alice.
Batman and Robin only beat up those BL because they allowed them to. The BL get off on the emotions of others, they like getting you really scared or really pissed off because that "flavors" the heart.