I don't really think Campbell & H. is a fine Spary gun (let say medium quality) but it always depend on what you're going to do with it. Almost all my airtools are from them (C&H) and they do what they're supposed to but they aren't pro tools (Magtools and so on are far better)...
My Spray Gun is from Devilbiss and if you're going to do some automotive 1:1 paint, I couldn't recommendent it enough. It's a nice tool to work with and

it's gravity feed

. Go for the "PLUS" Spray Gun which is the topline of the Spray Gun... it's like the IWATA Micron of the Spray Gun... I know you know what I mean ! But there's a price to pay to hold technoligie and craftmanship in a single package.
For the little metal cup, when I work with my Anthem (Badger 155), I always work with this kind of cup. A good little gizmo that can be charged while you're spraying offering you the capacity to blend colors while spraying. You'll love it for sure but don't think this will transform your Iwata into a Top (Gravity) Feed because it's not. Poor choice for a body though since you'll have to recharge quite often.