How to consistently install a set of packages?

[David <bouncingcats@gmail.com>]

I have a small number of personal different-hardware PCs, each with
the same set of different OS currently managed by grub v1. With
unison, rsync, scripts, and some care I successfully keep all OS and
the shared data in sync. It works great for my needs.

I now intend to add Debian wheezy and hope that it becomes my
preferred OS to replace an outdated Fedora. I already have a bare
minimal base install of wheezy on each PC, achieved by running
debian-installer manually in expert mode and unselecting everything on
the tasksel page.

I know the set of Debian packages I next want to install, without
recommends (like aptitude -R). These will be served locally by approx.
I keep the installation minimal for my needs only, and avoid gnome.

Because some packages create users and groups, I want to be sure that
these packages are installed in the same sequence on every PC so that
numeric uid & gid in /etc/passwd and /etc/group end up the same on all
PCs. This will make admin easier when keeping the shared data in sync
if the numeric uid and gid are the same in every OS.

To do the install I could use a shell script of many 'aptitude -R'
calls, but I don't know the required order to satisfy dependencies.

I could give 'aptitude -R' the large list of of packages, but how do I
know that its depsolver will always install the packages in the same
order? Perhaps I could do this once, and then get from some logfile
the actual order that was used?

google isnt helping me, results are dominated by debian-installer and
preseeding but I think that is not relevant to my question because I
already have installed debian manually. Please correct me if I am
wrong.

Are there any better methods I should be aware of, to ensure that
everywhere the packages are installed in the same sequence?