Ah welcome new person =P For one thing welcome to Supercheats! We all hope you enjoy your time here!
1)A clan(or team) is like a club. You can talk about certain things(what the purpose of the team is) and have fun!
2) Double postings is bad because it takes up room. If you quote someone you may double post, though don't quote someone to spam or something. In Graphics and Artwork, if you post artwork then you may double post.
Hope I helped
????- well. isn't this just interesting?