A rock lobster is just a distinct type of lobster. There are many kinds of lobster, such as the rock lobster and the blue spiny lobster.
Yes they eat each other only if food is scarce
A marine crustacean. A tasty dinner. See the Related Link below for more info on lobsters.
This answer relates to the Maine lobster. This is the lobster that has two big claws and lives around the north Atlantic off the coasts of Maine and Nova Scotia. This does NOT pertain to the spiny...
Lobster tail is just the tail. Lobster is the whole thing.