Which script to use to run answer site?

Any advice is appreciated

There are no pass-around scripts for running a help web site that I know of. You would have to create your own. The article below discusses different scripting languages. Before choosing a language, you should make sure that language is supported on the server you intend to use for your site.

http://www.mactech.com/articles/mactech/Vol.15/15.09/ScriptingLanguages/index.html