Don't worry about the questions thing. I just started two weeks ago and I had a shit-ton of questions as well. Rock crabs don't really require armor but if you get near a Hobgoblin then you should run away as they have really high accuracy. Rock crabs don't really hit high as well. Adamant armor should be more than enough for rock crabs.
Add me on MSN if you want to. It'll make conversing a lot faster.