Skippy, there aren't a list of potential permissions so admin access might be a bit excessive. You can very easily pick and choose which content or post types to enable and there are many that are easily set up via plugin. The admin UI is very clean and well laid out much like the front facing parts of the site. Most functionality is relatively intuitive and I've set sites up for non-technical family members to use. There are some browswer-based bookmarklets that come with the system that can help speed up posting in many cases too.
I've never needed to fiddle much with the theme for almost anything, though doing so isn't very difficult for folks with experience with HTML, CSS, and some PHP.
In general it's always been very simple and straightforward to run and manage Known. Even setting up API keys for syndicating to sites like Twitter, Facebook, LinkedIn, etc. is relatively straightforward.