Howdy. Is this part "* Don't change stuff that is not yours. I know that Xubuntu did this in the past when they had a stripped down gnome-session package that was different from the one in Ubuntu." that prevents using fedora-logo-icon in place of xfce-panel-menu icon (or 'computer' in lightdm, for that matter)?
And 'off-topic', here's an improved Mediterranean* theme the author sent me a while back after I asked him to make the selected items visible: https://dl.dropbox.com/u/80497678/MediterraneanNight_v1.11Beta.tar.gz