What's the deal with apt, debconf and dpkg-preconfig?

[ujr@physik.phy.tu-dresden.de (Ulf Jaenicke-Roessler)]

Hi,

 I'm about installing a new Debian machine, starting from a slink
 base installation, updating by apt and feeding package selections
 by dpkg --set-selections, immediately followed by a apt -d dselect-upgrade
 run.
 
 First of all I upgraded apt to the latest version from potato.
 I decided to install debconf next, hoping to prevent the recent
 problems with packages calling debconf wrongly.

 I got a message, that due to a perl upgrade perl-base needs
 to be temporarily removed. Furthermore some 'loop' occurred,
 and I should use APT::ForceLoopBreak. Okay, when I looked into
 the sample apt.conf, I read that I should NOT do that and the
 note pointed me to the man page. Unfortunately, I had not yet
 installed a man reader, but isn't it a contradiction between
 the example file/the man page and apt output?

 Nevertheless, the next problem doesn't depend on the ForceLoopBreak
 option: apt-get install debconf didn't work. I got an error message,
 that /bin/sh cannot find dpkg-preconfig, which is very obvious, since
 this file belongs to debconf, which wasn't installed yet.

 I solved it by dpkg -i debconf*deb, but I think, it should be done
 another way.

 BTW, I was able to fix the perl-base problem too, by dpkg -i perl*base*deb
 (which involved perl-base-5.004 and perl-base-5.005), but this should
 be changed too (in apt?).

 Otherwise, apt did a very good job in upgrading the system! :-)

 Thanks,

  Ulf