Here you go for building Sightly:
Java Doc: http://docs.adobe.com/content/docs/en/aem/6-0/develop/ref/javadoc/com/adobe/cq/sightly/WCMUse.html
Public Maven Repository: http://repo.adobe.com/nexus/content/repositories/releases/com/adobe/aem/aem-api/6.0.0.1/
Basically, following blog post also explains how to setup the AEM Maven dependencies: http://experiencedelivers.adobe.com/cemblog/en/experiencedelivers/2014/05/aem6-maven-dependencies.ht...
All of this is currently being added to the official documentation and should be published very soon.
Concerning the Eclipse Support, we are currently finishing a plugin that we try to make available within the next weeks. Thanks for your patience, stay tuned! ;)
The first version of that Eclipse plugin though will not have yet any special support for Sightly. For now, only the Brackets plugin that we intend to release in the next couple of days has some Sightly support (highlighting + code completion). But both plugins will offer a similar workflow that will allow you to work on your AEM project on the file system and the plugin automatically pushes changed files (or .content.xml files) to your running dev instance for checking out what changed. In addition to that, the Eclipse plugin will also have the capability to update bundles on your instance if some changes were performed in their code, and it will even be capable of hot code replacement if debug mode is turned on (i.e. skipping the bundle restart that can trigger various events).
Also following forum post might be of interest to you: Getting started with Sightly.
Hope that clarifies.
