I agree with Posde. Deleting an article may remove useful information, however obscure. Marking them as obsolete is better.
A similar thing happened to the MythTV wiki some time ago. Out of date information was removed. Basically, that eliminated the only available documentation on a small handful of hardware pieces,... available anywhere. Once that kind of information is lost, it's pretty much lost for good... as in Library of Alexandria lost...
As far as I've seen, the Wiki has a variety of "skins" that can be applied, from the basic default, to different layout and color schemes. So, it seems like some "theme" work has already been done. And, most people expect a wiki to look/work much like Wikipedia, by default at least. So, that kind of thing doesn't seem, to me at least, to be too big a priority.
I think the key is better indexing/organization, followed by edits for readability/simplicity and organization within the articles. Among the things that need more clarity for new users from the outset are; Networking structure & how-to, Basic system architecture (how the various software pieces fit together), Simple step-by-step tutorials for the most basic functionality, and a possibly a table for hardware compatibility (with links to the relevant articles and how-tos). It might be helpful to grade articles in terms of technical level (something like; basic, intermediate, advanced, expert & developer).
Before I started working on something else, I did a few very basic edits (some basic readability/updating, and starting a glossary page). I can do some things in a spare moment, or two, as well. My plate is pretty full, but wiki editing is/can be kind of a mind clearing diversion...