I think you should be using 'meego-sb-session' now - it replaced 'dui-sb-session'. There are still quite many places where 'dui' remains, so I understand the confusion. I don't know if dui-sb-session will still work, but I imagine there at least a few things that have been renamed (in /etc/meego-sb-session, I see 20input-method is invoking meego-im-uiserver, so that's one).

Yes, I think you don't really need the homescreen to develop applications, though I suppose you will want to check the .desktop files, icons and things like that. I'm not sure there any plans to make the homescreen work on top of maemo5. We are trying to get a new version of widgetsgallery out, but are having trouble with the repository. If anyone can help, please do.