I think feeding is something you need to figure out on your own as each piece is different. I have both a long tentacle plate coral (about 4" in diameter) and an elegance (about 5" in length but very narrow) and I feed each a small piece of krill or squid once a week.
I have had the plate for about 4 months and the elegance for one, and so far both are doing well.
Yes. I simply thaw them in a little bit of tank water, lightly stick them on a long thin wooden skewer and place it where their feelers can grab them. My Elegance will eat a piece in just a couple of minutes, my plate takes a little longer. I keep an eye on it as my shrimps try to steal the food.