Need to know how Apache, MySQL & PHP are installed

[jeffj]

I need to know how Apache, MySQL and PHP are installed on my VPS. I am posting in this forum rather than the PHP forum, since it may have more to do with VPS than PHP; excuse me if I should have posted elsewhere.

I have a VPS Rage account with four domains currently, and I have a few questions as I've been unsuccessful at installing a new PHP application -- MindTouch (i.e., DekiWiki). I am trying to install MindTouch from an RPM package, but it is failing dependencies because PHP is not installed as a package; it thinks PHP is not installed.

1. How is PHP installed on this system?
2. Can I install other dependencies (such as Mono) from a package?
3. As I'm already successfully running other PHP applications (Joomla, LifeType, Gallery) on some of my domains, what do I need to be careful about my PHP confguration during the MindTouch installation, so that I don't disturb these other apps?

The folks at MindTouch directed me to my VPS host to clarify these things before I can proceed.

Thank you in advance for your time in responding to my questions.