Thanks for comments in this thread, they've been helpful. :-)
I tried a factory reset, and then upgrading again to 2.4, but that didn't resolve the issues.
But I'm pleased to say I let my Touch update to 2.5 today, and it seems to have ironed out all the speedbumps I was finding on 2.4. The "touch me in 60 seconds or I'll go to sleep and sulk" bug appears to have gone, the shelves and library seem much more robust, the display settings are now responsive, and the sideloaded books have stopped shutting down when I use ToC links.
So; a much happier little Vegemite now! The system seems much faster now, too.
