.htaccess allow access to only one file

Hi guys..
I want to embed client side server files (like .js .css) and anything else (images, pdf files …) with php fopen function..

First of all, is this a good idea ( for load time, bandwith, SEO, etc) ?

Secondy, i want to make this rewriterules rules:

1) DirectoryIndex php/index.php
2) [url]http://www.bla-bla.com/cat1[/url] –> [url]http://www.bla-bla.com/php/index.php?cat=cat1[/url]
3) [url]http://www.bla-bla.com/cat1/subcat1[/url] –> [url]http://www.bla-bla.com/php/index.php?cat=cat1&subcat=subcat1[/url]
4) [url]http://www.bla-bla.com/cat1/subcat1/article1[/url] –> [url]http://www.bla-bla.com/php/index.php?cat=cat1&subcat=subcat1&article=article1[/url]
5) [url]http://www.bla-bla.com/cat1/subcat1/article1/info1[/url] –> [url]http://www.bla-bla.com/php/index.php?cat=cat1&subcat=subcat1&article=article1&info=info1[/url]
6) Deny Access To Everyone Except PHP fopen to all files except php/index.php [B](only with the above ways)[/B]
7) Redirect all request that deny from 6) to [url]http://www.bla-bla.com/php/index.php?error=404[/url] with a 404 error flag (SEO friendly if possible)

Is all of this conditions possible?
Any help?

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