Web Design Intellectual Rights

[]Are words copyrights? For example, if www.Digg.com uses the word “bury” to describe hidden comments, may I use the word “bury” for similar purposes?
]Are ideas copyrighted? For example, if www.Threadless.com allows people to submit t-shirt designs and they print the highest rated designs. Am I allowed to do a similar idea? Actually, there are tons of copies - www.DesignByHumans.com - to name one.
[]Are color schemes copyrighted?
]Are you allowed to use a existing domain as a prefix or suffix to your own domain? For example, may I create www.FlickrGame.com if I wanted to make a photographic flash game using Flickr’s API?