The site redevelopment continues, but somewhat slower. Technology has been the main sticking point, and it hasn't been clear until today whether Drupal (plus the otherwise excellent Panels module) could support exactly what it was I wanted to do. It turns out that it is, but it's pretty difficult to work out exactly how to configure and build the necessary components.
Like working with so many other OS projects, implementing something for the first time in Drupal can sometimes be a frustrating experience; the second or maybe fourth time is so straightforward that you can hardly believe you ever had problems figuring out how it was done. Once I've got some of the key components in place, I'll have to write some howto blogposts alongside descriptions of the rationale.