It's based on the open source Wikka engine, and is extensible in many directions using plugins; it has native support for cool features such as MindMaps so creating easy-to-navigate, site-at-a-glance alternate indexes tailored to suit individual needs is quite easy. The whole thing can be re-indexed easily once the data is up.
Editing in the PARISWiki is very user-friendly. A brief tutorial is available here, step by step video tutorials here, and full documentation here. Hit the brief tutorials first, then the videos, and you'll have everything you need to start posting tips, cutting and pasting FAQs found in the newsgroup, fixing spelling or errors or adding a key topic page.