Replying to @K Meyers's post:
I believe that this may depend on the specific wiki software or service you're using. In many (or most?) wikis, you can restrict specific sections or even specific pages. But different wiki tools permit greater or less flexibility in, for instance, whether you can have different restrictions on a sub-page than you do on its parent.
I believe that the management of commenting may similarly vary from wiki to wiki; typically a wiki will provide a hierarchy of privileges and in some cases editing and commenting are treated separately (so a user might be able only to comment, not to edit). In other cases those two sets of privileges might be grouped together (as I believe they are in PBWiki, for instance).
In both cases, the documentation for the specific wiki you're thinking of using should hopefully include answers to these questions.
Although it doesn't address these specific questions, WikiMatrix (http://www.wikimatrix.org/) provides a useful comparison tool that lets you compare features of a number of popular wiki tools (for instance, if you need to find a wiki that will support right-to-left text and WYSIWIG editing).