Replied to the registration process info already elsewhere.
As for the sidebar, feel free to adjust it with updated content. See https://techbase.kde.org/MediaWiki:Sidebar
Since KDE userbase and Techbase share the way on how to modify pages, probably it make sense to keep the link to the userbase documentation without duplication. I suggest to add to the "Relevance" section two subsections: one for userbase and one for techbase where we explain what kind of content should be posted. Does it make sense?