How to view PHP on live site

No, as it is interpreted on the server-side and the results are sent to the user. If you want to view the source code of a site you control in-browser, consider the FirePHP extension for Firebug, or just access your site files with your preferred method.

Usually, no, as others have said, unless of course this is something you want to be the case. Then you can set it up so that using .phps (or any other extension really, but this is the norm) will display the source code of the page (with syntax coloring I believe). Something like:

AddHandler application/x-httpd-php-source .phps

in your apache configuration should do the trick.

Note, you will need to save your .php files with a .phps for their source to be displayed.

Everyone is wrong! Yes, it is possible! But if you do see the code in your web browser then this would be a serious security breach or some major trouble in the web server. I've seen it happen once, where some dumb administrator had removed the PHP extension for IIS thus the browser provided all sources as text files instead of executing them.

Then again, there is an alternative method, which is through FTP. Most websites give access to their file system through FTP, so administrators don't need physical access to the system. You will need to know username and password, plus the FTP address to get access, but once you have this information, you have access to the whole site. Useful for administrators, yet also a very good reason to be very careful with passwords.