Questions Questions Questions

Firstly I have a problem renaming a file through php. It says permission denied though i chmod ed the file to 777. It's worked fine on other servers though!! I'd also like to know if multiple includes work. For example I include a file and that file includes another file. Will it work?? I'd also like to know a script or a command that detects your browser and if it is IE 4.0 or above / netscape 4.0 or abour it sets $browser to 1 and for any other browser $browser to 0 Is it possible to run shell commands. Like commands we type in telnet. I will also need to login as root so please consider how I would enter the password.