Need some suggestion for showing notification in Android

Hi,

I did Notification in Xamarin.Android and just wondering how to implement it in Xamarin.Forms. I need some ideas regarding this.

1) In Xamarin.Android i used Alarm Manager to start service for every 1 minute to check is there any notification. In Forms whether I need to do it separately for each platform or some common class is available for this, so that i can put it in shared?
2) In Xamarin.Android onclick of notification i am starting the activity, but in Forms, if I have service in Android, how to start Forms page from Android service.

Which is the best way to implement this?