Beginner with firebase

You can upgrade the version of angular-fire, probably the version you are using does not support $firebaseArray .

Try to change the import of your libs to these:

<!-- Firebase -->
<script src="https://www.gstatic.com/firebasejs/3.3.0/firebase.js"></script><!--AngularFire--><scriptsrc="https://cdn.firebase.com/libs/angularfire/2.0.1/angularfire.min.js"></script>

If it works you can download the updated libs and import them as they used to.

  

I'd better declare my firebase settings in the "app" or   "index"? I've seen two ways to do it on the web.

I think this is more a question of "good practices", I particularly always use in app.js because this way the project gets more organized

Ref: Quickstart | AngularFire