Does it really cool it? It's just a piece of aluminum rite?

Where is the option that will show how much more space my HD has in the desktop? I have seen that option before but cant seem to find it now.

Try the Mac shop in Ikano. I got mine there. They didn't have stock when I went to buy but they took the initiative to get it from another branch. Go look for the guy called Leon. Quite friendly and helpful.