If your making your own case, ditch the 80mm fans and set it up to use 120mm fans. More flow for less noise
And I would say use aluminum for construction. Cheap and fairly easy to work with. Just make sure you put a stiffner bar in the middle of the "back side" (behind the mb) to keep it sturdy if you make it tall.
Regarding radiation - much less than what you get from a lot of monitors (or a cellphone or....) and the levels are low enough that unless you do what Fixitt does and keep your head in your case all day, not even worth thinking about.