Front-end development workflow (Polymer + Ember)

Most of my working time I have been spending on backend development(RoR), but now I'm building standalone front-end app. So I have several questions about orgranizing my work. My questions are about Ember and Polymer, but I will be very pleased to see also generalized techniques (e.g. Angular, Flux, React, whatever-front-end-library-or-framework).

1. Development and production

In RoR I was able to set my environment (test, development, production). Working with my standalone front-end app I have to integrate it with some backend API. For development env I need to work via JSON with sandbox.test.com and for production with api.test.com. How can I do it clear with Ember?

2. Deploy

I want to use Capistrano for deployment of my front-end project. Are there any best-practices of front-end apps deployment?