Debian-friendly upstream best practices?

[Daniel Pocock <daniel@pocock.com.au>]

I am involved in several projects where I am either the founder of the 
project (e.g. dynalogin) or a contributor with full access to the 
repository (e.g. Ganglia, reSIProcate, flactag)

There are also a couple of projects where I don't have any role, but I 
would like to package the code for Debian.

I'm just trying to establish the pattern I should be following

a) for those projects where I have no role, no commit rights, etc, I 
presume that I should just use git-buildpackage, create a distinct 
repository to track debian/ stuff, and follow the normal structure 
(master and upstream branches)

b) however, for the other projects where I can potentially include 
debian/ stuff in the upstream repo:

- Is there any compelling reason to create a separate repo for 
debianisation?  Or it is perfectly fine (in a technical sense) to have 
the debian branch in the upstream repo if nobody else there has objections?

- is it reasonable for the upstream repo to have a Debian branch, 
inverting the normal use-case of git-buildpackage?  e.g gbp.conf:

      [DEFAULT]
      upstream-branch=master   (not upstream)
      debian-branch=debian     (not master)

or possibly:

      [DEFAULT]
      upstream-branch=master
      debian-branch=packaging/debian

- in the `normal' git-buildpackage use case, I notice `upstream' branch 
has one commit for each real release, yet if git-buildpackage is used 
with a real upstream repo, the `upstream' branch may actually have many 
small commits that are not releases.  Does this cause any problems?

- when such a combined repo is used (upstream and debian branches all in 
the same repo), can tagging be handled automatically?  I was thinking 
that tags should be in some format such as

3.3.5
packaging/debian/3.3.5-1  (or 3.3.5/1 perhaps?)
packaging/debian/3.3.5-2

- In that example, the 3.3.5 tag is created by the upstream release 
process, not by running git-import-orig - will there be any problem if 
git-import-orig is never run?

From reading the man pages, my impression is that I can use a config 
such as I describe above, and use commands like these:

git-buildpackage \
  --git-tag --git-debian-tag=packaging/debian/%(version)s \
  --git-upstream-branch=master \
  --git-upstream-tree=TAG \
  --git-debian-branch=packaging/debian

git-buildpackage \
  --git-tag --git-debian-tag=packaging/debian/%(version)s \
  --git-upstream-branch=master \
  --git-pristine-tar --git-tarball-dir=/home/daniel/upstream-tarballs/ \
  --git-debian-branch=packaging/debian

Can anyone make any comments on these questions, how I should proceed, 
best examples to follow, howtos I should read, etc?