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