Outdoor Fireplace

Hiya Folks, For all you masons out there, I've got a question or two regarding outdoor fireplaces. I'm looking to build my own Kiva fireplace outdoors in our front courtyard. I've started looking at pre-cast units as well as the Superior Clay products (aka Rumford) and have decided just to do it all on my own. I've stopped into a few suppliers asking questions and they always give me a price for a damper and smoke chamber. Basically I have two questions at this point. 1. Do I need a damper for something that's going to see use outdoors? 2. Can I simply shape my own smoke chamber with morter and brick vs. buying a pre-cast one? I definitely will be installing Flue and I'm sure that would be easier to install if I had a pre-cast smoke chamber to work around but just not sure if I can't just shape it myself. Cheers, cc