Solution to the xserver-xfree86 install problem: In the install script /var/lib/dpkg/info/xserver-xfree86.postinst line 60 must be corrected from
ln -sf /etc/X11/X "$this_server" (MISTAKE!) to ln -sf "$this_server" /etc/X11/X (a quite common mistake which I myself often go for). Greetings, joachim