do they need a very mature tank to live in: A six month or older is fine
lots of live rock: They love to explore, very active..so yes, for their overall wellbeing
what do they eat: Pellet, frozen mysis, a tiny bit of Formula2 now and then, I'm sure pods if they are available
are they aggressive: Not at all, in my experience
and what is their care level: Easy. Very social, active and entertaining.
COVER your tank.
Pics would also be great.