You did not understand my question. Biography and sales pitch? I am not promoting links here :-).
I just wanted to know if I can use certain information while writing biographies. For example: If I am writing a John Lennon bio and collect info on his life can I use them worry-free? Or do I have to inform the sites and take permission?
It depends, are you "copying" or are you "doing research". Re-writing is a form of copying.
If you take notes on facts, and then you write your own copy based on your notes, that is doing research.
Think about what was expected of you when it came to writing your reports back in high school. If your teacher would approve of how you went about writing the report, then it probably is not copyright infringement.
But if you do get a significant amount of your information from a couple of major sites, then you should give them some credit.