Ok, it works now. Here is the final code:
*SERVER_DOCUMENT_ROOT = the actual server document root which I discovered using your tellme.php technique.
<?php if(file_exists('SERVER_DOCUMENT_ROOT'.$post->post_name.'.php')) { include 'SERVER_DOCUMENT_ROOT' . $post->post_name .'.php' ; } ?>
The code was missing some brackets but it works! SO the idea behind this code is to look at the page slug and then include the content from another .php file on the server with the same name as the page slug.
Doing so will allow me to replicate a website and control the content across all of the other sites with ONE template and some master .php files.
Through a similar template, it will utilize the loop and allow the admin of the other sites to add custom content to certain pages. This should work out just fine. Thanks for all your great work Esmi, I hope this information helps others!