Does php Filesystem functions work through a php FTP Function connection? If so, how would it work?

ex: is_dir(), file_exists(), is_writeable() ect. ??

It depends of the php version you are using. If it's verion 5 or higher, then yes, it's possible. It's possible, but very limited, in version 4. In PHP 3 or lower it's impossible.

For more details visit: http://be.php.net/manual/en/wrappers.ftp.php