You can drag all the palettes out of the main window and onto the secondary screen -- so that's covered. I think all palettes individually will fit in 640x480, but I haven't tested. My secondary monitor is already 1280x1024, and it's actually a long time since I last had a computer with a 1024x768 screen -- my wonderful Lenovo X61t with built-in wacom digitizer.
As for accessibility, yes... We actually have huge problems there. We used to have someone on the team we knew enough to make sure that the Calligra (back then, KOffice) apps were properly accessible, but we lost that knowledge, unfortunately.