Questions on GCM -> FCM migration

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My company is migrating its Android apps from GCM -> FCM. Following UA's & Google's guides, everything is working as expected. However, we have vestiges of our old UA GCM code remaining, I'd like confirmation that removing the following will have no ill effects. I've been unable to locate references to the following in UA's migration documentation:

1. Our UA/GCM code included CoreReceiver in our Manifest, it looks like this can be safely removed:
   
   <receiver android:name="com.urbanairship.CoreReceiver" android:exported="false">
   <intent-filter android:priority="-999">
   <action android:name="com.urbanairship.push.OPENED"/>
   <category android:name="***"/>
   </intent-filter>
   </receiver>
   
   
2. We are referencing PlayServicesErrorActivity in our Manifest; we also have an old reference to CoreActivity. Can the reference to CoreActivity be removed while retaining PlayServicesErrorActivity?
   
   <activity android:name="com.urbanairship.CoreActivity"/>
   
   
3. We have an old reference to ActionService in our Manifest, but it is my understanding that this is not needed if we are not using any Action Situations or custom Actions in our app:
   
   <service android:name="com.urbanairship.actions.ActionService"/>