I am relatively new to Angular, but wouldn't you want to have the comments be a Factory using ngResource? If the comments are restful then it seems much easier.
Theoretically yes, but ngResource is kind of the achilles' heel of AngularJS right now. You're often better off using a different library or making your own class with $http requests.
I'm using AngularJS 1.1.5 and ngResource in my project and it works quite nice. I wouldn't discourage people from learning the hard way. However, +1 for Restangular.