Port 80: you need root privileges to do that, and the Apache server which ships with the Mac (as Personal Web Server or somesuch) will be using that port, if it's turned on, so you can't bind both the Apache and Django app at the same time. But you can configure Apache to use mod_proxy to reach the Django app.
- you want an externally resolvable
hostname so people can find where
you are; if you don't have your own
domain, start out with something
- getting through to you: one or the
other (or perhaps both) of the ADSL
Modem and the WiFi router will be
doing NAT to let you have multiple
machines at home. You want to open
a pinhole in the NATting device,
pointing port 80 to one particular
machine on the internal LAN. You'll
also want to make sure that the DHCP
server (part of the same device)
always issues the same IP to that
device, so lock that MAC address in
to a particular IP.
Finally: a popular FB app will absolutely kill your home network connection and one machine will not be able to host it, so while what you're doing might be fine for initial development work, if it looks like the app will be popular you'd better be prepared to spend quite a bit of money on professional hosting.