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Can't help you with the first question I'm afraid, and I'm not sure I can with the second, but I'll give it a go!
From the sounds of it, the server is set up to deny permission to a folder unless a specific, existing file is requested. You can do this on hosted servers, for example, with a .htaccess file to prevent people seeing an index page of everything in the directory.
So it just looks to me that the server isn't configured to look for an index.php file.
Of course, I could be way off target - I but if you don't fcuk up you'll never learn! ;)