In order to integrate Facebook login, you can use App42 Unity SDK in which you can call DoFBOAuthAndGetToken method. It will not require Facebook SDK. For more detail of Facebook login using App42 Unity SDK, please have a look at this link.
For Google Plus Login as of now we don't have any sample in Unity, you need to integrate by your own. In order to send notification for invite or game out, you can use App42 Push Notification service. Please have a look at below links and let us know if you required any help from our side.