Past DebConfs, what you need to know
There have been some DebConfs in the past. They're all documented on the
DebConf Wiki 
After the conference (usually about a year later) the conference team
puts out a report. These give us a pretty good idea of what we need to
do. Expected drop-out rates, issues encountered, sponsorship levels,
etc. Find the reports in the debconf-data family of git repos .
Many of the working documents (budgets, etc.) can also be found here.
On that topic, if you don't have an account on alioth , go and create
one . You'll need it to push to any Debian git repos.
For attendee numbers, I'd look at DebConf 12 in Nicaragua. It was fairly
out of the way (although close to North America), and so had a lower
attendance. I'd expect something similar for us.
H: +27 21 461 1230 C: +27 72 419 8559