How to configure the fields in the report created by the Content Audit module?
Have a look at the article about "Content inventory and content audit with Views". Here is an intro of it:


  Do you know the exact state of the content in your large Drupal site? Thinking of revamping, redesigning or upgrading your site? If you answered 'no!' to the first question or 'yes!' to the second question, it's time for content audit.
  
  In this blog post, I cover the what, why, who, when, where and how's of content audits. I've conducted a few small content audits, and I'm leading a much bigger one, on Drupal.org.


It's a pretty old article already (from 2011), and still contains Views2 screenprints. But it includes a lot of interesting details that should help to answer your question.

What is also interesting in this article are the recommendations to actually "evaluate your content", via a combination of these options (quote from the same article):


  
  Option A (Export): export this view to CSV and manage your content audit in spreadsheet software or Google Docs. The Views Bonus Pack module will let you export the view as a CVS file.
  Pro: Less data to store in your database
  Con: Your inventory is almost immediately outdated; will be extra time-consuming to update on a regular basis
  Option B (Flags): 'Flag' content that needs to be updated using the Flag module. You can adjust the flag settings so that only certain roles can use this flag, and then set which content types can be flagged (or set it as global). You can then add the Flag to the content audit view, and/or create a separate view of nodes that have been flagged. However, marking something as "needs work" doesn't provide enough detail, so you'll want to record notes somehow (see Option C). You can create additional flags for each type of action to be taken, e.g. "needs style review" or "redundant", without the casual visitor even knowing, while keeping your content team in the loop.
  Option C: Keep 'audit notes' field on each content type in Drupal site database with the Annotate module or by creating a field on the nodes.
  Option D: Use the Content Audit feature module, which constructs the View, and will soon have configured Annotation (this hasn't been built yet).
  Option E: Create another node type called Audit notes, and once filled in, then nodereference the node it covers. Then, it's easy to build a view of the Audit notes (I'm also wondering whether this could be a custom bit of code to automagically do this, then include in the Content Audit module).
  


Some more module suggestions to further enhance your content auditing experience (which you may want to use as complements to configuration facilities available in the Content Audit module):


Consider using the Flag module (as in that "Option B" above). And then possibly combine anything that might get flagged with the Rules module to trigger things like:


Unpublish and/or delete this content.
Add it to some type of review (workflow) process, like content accuracy, spell checking, etc.
Notify authors via eMails, like: "Please review this content, and use any of the available flags to indicate what your recommended action for it should be".

Auditors often like charts to visualize what's being audited (a picture is worth more then 1000 words ...). By simply installing (and enabling) the Charts module, and without any additional configuration, you get some Out-of-the-box examples that come with this module (in the format of some charts and/or a Views table display). They contain data about the total number of nodes for each of the available content types. And these data are limited to the nodes for which the user has permission to view them. Visit the Charts demo site for an online preview of of these out-of-the-box examples.