Basic Seo and Website Improvement

I'm looking at doing these things to improve my website seo improved and also basic site adjustments: 1. canocialising a website - i believe this can effect ranking as otherwise it can duplicate indexing ie. [login to view URL] and theshiftmusic.com. not sure if this is true? 2. on one of my pages the flash plugin needs centering 3. simple internal site optimisation 4. make "donate" / "buy" button work