Interesting... I've had a much better experience with MediaWiki. It requires contributors to use Wikitext (like BBCode, but more powerful and complicated), which I find users are becoming less tolerant of. However, contributing to a wiki is a significant commitment anyway. One needs to learn about conflict resolution and other norms of the community if one is going to participate in the group writing project. In that sense, the technical hurdle of the wikitext might be a good screening tool.
The forum mentioned above, mwusers, is a little dead, though. I find that more responsive support from developers, etc., can be had from the
mediawiki-l list sponsored by the Wikimedia Foundation. It's archives can be searched on gossamer threads.
I think Common.css gets loaded on its own. Just Google it.
The wiki I contribute to and administrate can be found at
http://www.tmswiki.org/ . It's a little rough, still, because all of the pages were brought over from an archive by a PHP script that had to translate from the HTML to the wikitext. Since the HTML was human modified (from a Wetpaint wiki), this did not go smoothly.