If i have links on higher ranking sites than my own, and I have there a link to my php forum index...index.php...will google crawl that, in due course*** or should I make these links, mysite.com...
To ensure that those links count towards your homepage's link profile, you should have a redirect setup. So if someone goes to http://www.mysite.com/index.php it redirects them to just http://www.mysite.com/
If you use a 401 redirection, no one will know the difference. I believe that Google would not even see a JavaScript redirection, so don't attempt one of those, as they will probably annoy your visitors and won't serve a purpose (irony). function curPageURL() { $pageURL = 'http'; if ($_SERVER["HTTPS"] == "on") {$pageURL .= "s";} $pageURL .= "://"; if ($_SERVER["SERVER_PORT"] != "80") { $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"]; } else { $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"]; } return $pageURL; } Place that code in the header of all your pages, for example, and you notice that "yoursite.com" will load as "http://www.yoursite.com". I don't know if the above code will help with your "index.php" problem, but it will prevent duplicate content on much of your site.
Search engines are more interested in the Content-Type HTTP header than they are the file extension. For instance there are some news sites that have *.ece pages, and they're indexed just fine because of their text/html Content-Type.
No, the 301 redirects don't! Choose either version with the WWW or without it to use, then redirect index.php with both - www prefix and not, and the version of URL you wont use to the preferred one to avoid having duplicated content on home page. Otherwise you wont have any issues with the .php crawling at all...