Spacemacs is such a great framework for development (and more). I echo shadeless's comments. I've been working with it since March and I've become exponentially more productive since.
Thanks for the question. I'll update the article to explain that more indepth later today. It's 'binding' the value to the model of that DOM element in the view.
We go in-depth into the model component on the next article.
I totally agree. We work hard to make these tutorials approachable. In this series, we're doing both: discussing core features as well as building an app alongside it. The "tough" part of it is that AngularJS has a bit of a learning curve, so some concepts "need" to be explained, while others (later in this series) will be more "hands on."
In terms of discussing AngularJS, there is the client-side front-end and back-end view and the server-side view. We address talking to a backend later in the series, stay tuned.
We'll address these in our next article (we get a lot of requests for handling user auth). This series is specifically intended on introducing AngularJS to beginner and intermediate users.