I am also trying to study Ionic framework to use with an Android app. Ionic seems to be a very good framework, but the lack of documentation is blocking me from advancing.
From what I have seen so far, it looks like Ionic+Angular already integrates Cordova. So you don't need to create a Cordova app anymore, just create an Ionic app and it has Cordova underneath it:
Did it using Ionic CLI, which uses ionic-angular-cordova-seed
About the backend, Angular provides $http and $resource for AJAX requests, take a look at the Angular documentation, I assume Ionic didn't change the way Angular makes these calls.
My conclusion: I think when Ionic becomes a more mature framework (which won't take long) with better documentation, it will be the best UI framework. From what I have seem, it looks very native with very good performance. And I still plan to keep going with it for having no better option, although it is taking me some time because there are things I still can't understand.