I know google penalizes sites that have duplicate content does this mean duplicate content across many pages of the same site? What does duplicate content mean? i "include" my headers, footers, navbars and/or advertisements using PHP on all my website pages...surely this is the most literal meaning of "duplicate", but i'm sure that google rankings wont be affected by such seemingly duplicate content.
Domain name vs content:
If i have a website that ranks highly in google, and i change a lot of the content on it, will the fact that my domain name is highly ranked help preserve my pagerank?
Lets say i pay the pay-per-click. Does the traffic generated by the sponsored advertising count towards your natural search ranking whatsoever...or does it hurt it?