To refresh this document, perhaps it would be worth mentioning more modern methods to serve php content under apache httpd.
Specifically, the preferred method is now fastcgi, using either of those recipes:
(mod_fastcgi, httpd 2.2)
(mod_fcgid, httpd 2.2)
(mod_proxy_fcgi, httpd 2.4)
While the legacy mod_php approach is still applicable for some older installations, the fastcgi method is much faster, and require much less RAM to operate, based on similar traffic patterns.