Safe_mode / PHP3 and 4

Hello, I installed Apache-1.3.27 + PHP-4.3.1 as static. So, I have two doubts: 1. Someone has told me that Safe_mode don't permit any intaration with the system like phpinfo() and the users couldn't execute a cat, ls and so on. I enabled PHP safe_mode and executed a test with phpinfo() and it showed the system informations... :-/ What exactly safe_mode does? How can I deny any interation between PHP and the OS commands? 2. I'd like to install support for PHP3 and PHP4. reading the manuals, it says to compile apache with the option --with-apx, but it didn't work with parameter --with-apache. Can I install PHP3 and PHP4 with apache in static mode? How can I do it? Thank's Ronan