What is the use of the copper, silver and gold icons next to usernames?
Is there something on this site I can buy to pimp my account?
I'm kind of lost on this one, hope it's the right place to ask this question.
It's the number of bronze, silver and gold badges you've earned. No, you can't buy them. You earn them for participating in the site in various helpful ways.
Here's a list of badges and how to get them (that's the same link you get when click on the "Badges" button between "Users" and "Unanswered" on the top of the site).