There is already a DNS entry for the domain you are trying to use. Please choose another one. If you are the one the domain belongs, post back here and I'll see with you.
The files in the www folder (or the public_html folder) are not system important files. They are the files that show up on your website. You can re-upload them.
do a print_r() or a var_dump() of the $_SERVER array, to see if the header you are looking for is included.
Try this function : apache_request_headers() http://ca2.php.net/manual/en/function.apache-request-headers.php