I'm really not sure what the heck the outer vent control valve does, but your carb 100% does not need it to run, so I would not worry about it. I've never seen a rebuild kit come with the diaphragm, but usually the gasket.

And yes, I have found that other kits come with more little things than the NAPA kit, but its usually useless stuff like new screws and extra clips. As long as its got 4 diaphragms, the main gaskets and jets (not as important), you're all set.

-Scerb

http://www.scerbfab.com/carb_faq.html