How to block all apps notification except sms and calls?
It is possible with  Macrodroid automation app (free upto 5 macros) and real easy to learn

Trigger: Notification &rarr; Notification Received  &rarr; Select app  &rarr; Text content  &rarr; Any  &rarr; ok

Action: Clear Notifications  &rarr; choose apps from drop down (don't use clear all, since it has phone and SMS )&rarr; ok Text content  &rarr; Any  &rarr; ok

Constraints: Leave blank

Name the macro , save and you are safe from machine gun fire :)