Question about having an always clean base system in Debian Sid

[Geek87 <geek87@gmx.com>]

Hi all!

I'm new on the list so I hope my question is not stupid and I'm asking
it in the good list.

I have Sid installed on my computer and I would like to know how to keep
my base system (~prequired, ~pimportant, ~pstandard) always clean and up
to date automatically: if package A is no longer needed it should be
removed automatically and if package B is new and with one of the 3
priority above it should be installed automatically.

For the autoremove problem I found a solution: I put all ~prequired,
~pimportant, ~pstandard packages in "automatically installed" state and
put "~prequired, ~pimportant, ~pstandard" in the APT::NeverAutoRemove
directive of the apt.conf file. In this case every package that is
repacked with a new priority not in the 3 above will be automatically
removed unless there is a dependence on it.

For the autoinstall problem I didn't face the situation yet but I don't
know how I'll do.

I also would like to have it working similarly for the tasks: for
example if I have a task "Mail server" installed depending on Sendmail
and that the new version of this task now depends on Postfix, I would
like Sendmail to be automatically removed and Postfix to be
automatically installed. The technique above doesn't work for the tasks.

Do you have any idea? Is the technique I used bad and dirty?

Thanks in advance.

Geek87