Question about Debian build infrastructure

[Kyle Edwards <kyle.edwards@kitware.com>]

Hello all,

I have been preparing Ubuntu releases for CMake on our own APT
repository for several months now. We did this by preparing our own
repository infrastructure - we have a machine that builds packages, and
a machine that hosts an Aptly instance and pushes the repository to our
web server. However, all of these things had a lot of manual steps to
set up and use, and I'm wondering how Debian handles this problem. Here
are some of my questions:

1. What software do the official Debian repositories use? Do they use
Aptly or reprepro or something else? Is there a downloadable OS image
which comes with this pre-set up? Does it run on a cron job or does it
have some sort of continuous monitoring? (We have ours run on a cron
job every 10 minutes.)
2. According to https://wiki.debian.org/BuilddSetup, there seems to be
a distinction between the build broker (wanna-build) and the build
workers (buildd). Do either of these roles have their own OS images one
can download?
3. I understand that source packages are signed by developers before
being sent to the build farm, but what about the binary packages built
by the build farm and uploaded to the repository? Do the build farm
servers have their own GPG keys? Does the repository server recognize
these keys?

Thanks in advance, all this info would be helpful for me as I expand
our Ubuntu build infrastructure.

Kyle