Quick Pattern to follow to debug Remote Event Receivers for List Events for lists in the Host Web. So far I have not been able to debug these successfully. I have been able to when the list and the RER’s are created in the App Web Project and attached to App Web Lists. So it seems to me we could create them in the App web to develop and test them and when working move them into the Host Web.
Also remember any object you what created in the Host web has to be created using code and of course will need the right permissions to do so. These assets can be created either when the app is first run, from a App install event (which makes the app minimally partly a Provider-Hosted App or provisioned from a non app client side application – eg a console application using SCOM.