How django works with emberjs?

someone may help me to figure out what part take EmberJS in a web application? Currently I'm using Django for the back-end and I love it, but I'd like to speed up my applications and after reading a bit of docs, I thought that a front-end framework is what I need. After reading a bit of ember, I saw there are a lot of concept that are the same of Django, like models, routes, templates and so on.

This get me a bit confused, because I always saw a front-end framework something that define the "behaviour". As Jon Duckett says in the book Javascript & JQuery, HTML is for the content, CSS for the presentation, JS for the behaviour. After playing a bit with JQuery & Ajax I've been able to speed up a bit my small applications, but is not enough... A lot of developer are moving to ReactJS, AngularJS, EmberJS to create real-time web apps and if waiting 2 seconds for a response was ok in 2010, now end users are accustomed to get real-time response (thanks to google and facebook, just to cite someone).

Some questions:

1) I saw EmbjerJS has models. IS the same concept of models in django? I mean, is possible creating web application only with a front-end framework like EmberJS? 2) Why I need a REST API? If I use a front-end framework like EmberJS, the JS stuffs can't be included in the template and rendered by django template system? 3) If I use EmberJS what kind of stack I have in applications? Looks like I need only django models with ORM that talk with the DB, a REST API that retrieve data and a front-end that display those data... but How the data are updated? 4) There are some resource that explain this stack in detail and provide a tutorial like django polls with emberjs or contact form?