Hello,
If someone can download you PHP files without them being processed, you must have made a mistake in the configuration of your server.
The wp-config.php file can be placed just outside the public directory (there is discussion about it on the officiel website, with some people saying it's an improvement and some saying the opposite but I don't remember all their arguments).
If I'm not mistaken, an url toolkit like that should replace the Apache Rule given by the official wordpress website :
<files wp-config.php>
order allow,deny
deny from all
</files>
UrlToolkit {
ToolkitID = wpconfig
Match wp-config.php DenyAccess
}