red lobster/crayfish

I just bought 2 red lobster or is it a crayfish, not sure... from clementi. So I need some information on keeping them.

I just need some basic information on how to keep them. Currently I keep them in a 2 feet tank.

1) Do i put in a lot of water or a little bit?
2) What do I feed them?
3) Do I need a cover for the tank to prevent escape?