I want to set up a 10g invert tank. I am looking at an all inclusive kit. What will I need just for the inverts? Do I do the same thing as if I were adding fish to it? The things I like are crabs, shrimp, sea stars. Is it possible to keep them all together? I like the Halloween Hermit Crab. I looked and can't find if it stays submerged all the time or if it has to have air. I am guessing I will need live rock regardless correct?