How i can call native facebook application for login & other stuff, from my Xamarin Application?
Have you taken a look at Xamarin.Social to integrate your app with Facebook? (http://components.xamarin.com/view/xamarin.social/) Perhaps that might be a better approach than having a dependency on an external native app. Just a thought.
Xamarin Inc., as a wholly-owned Microsoft subsidiary acting as a separate legal entity, adheres to the Microsoft Privacy Statement: Privacy & cookies