Thanks for the detailed plan of attack!
Re: mediawiki vs. dokuwiki
Currently the userhelp is based on a SilverStripe installation, which isn't an inherently bad thing. I'd expect the group of editors to be quite small, to the extent of 2-3 per language. This smaller group could just as well collaborate in a CMS context, and use our upcoming workflow (publication-approval) mechanisms. We can still gather input and errata through user comments. The barrier of entry for a userhelp author is naturally higher (apply for a CMS account rather than anonymous edit), but given the fact that the userhelp is rather prominently linked in all SilverStripe installations out there leads me to think that "quick fixes" should be avoided anyway - there should be a light editorial review process. So: I'd suggest sticking with the tool we know (SilverStripe), and taking it from there.
Re: Audio/Video Learning
Do people have experiences with this? Do your clients actually use it? I would put the priority for videocasts far below a well-written handbook, but perhaps thats just because i'm a techie?
Re: Comments on userhelp
Thats an easy one - just enable the disqus service, see doc.silverstripe.com :)
Again, SilverStripe can help here - although page translations are still early stage...
Obviously its a big motiviation and criteria for most non-english developers to have user-level learning resources in their native tongue, so this is a critical factor which we need to improve on one way or the other.
The most important task at hand is in my opinion: review the existing content, update text and screenshots to fit 2.3. If this involves restructuring the content - walec51, could you elaborate a table of contents for this?