I am not a fabricator so I don't know the little details. For the dzus fasteners, I know there are many types. Button head or flush - Use the button heads if you don't want to dimple the panel for flush mounts. Then there are different materials, aluminum, stainless, steel. That is pretty much cost and preference. For the dzus plates, they come in different styles, lightened, standard, etc.
Call a sheet metal fab shop and get their recommendation.
For the material, I think you want to use 2024 or 5052. Maybe 07fj will chime in about that. Thickness can vary.