I didn't give advice about something I don't know about. Obviously I have used DMZ if I'm offering it as a solution, it opens ports.
It sounds to me like you aren't very familiar with routers and Internet devices. You need to take time to learn configuration and terms like DMZ before you try to help others. Especially if you don't understand how a dynamic IP works.
You don't know what your talking about. DMZ disables all of your routers security features. Port forwarding isn't "Opening Ports", it's telling your router to direct data sent on a port to a certain internal IP.
Usually when one refers to a "Static IP" they are referring to paying your ISP so your external IP doesn't change. Having an external static IP doesn't change your ability to port forward. If you were referring to turning off your DCHP so you have a static internal IP, it's something that you may or may not need to do.
@OP: Don't listen to Sheath, and just google "airport express UPnP". I'm sure there are many guides out there.