Ergo uses Bamboo and Buckminster for release builds and branch builds. Depending on what you are interested in, the most stable builds will be the release branches since those will go through an alpha, beta, final release cycle. If you are looking for more stable builds that have newer features, use the link found in the master branch section. If you want to try bleeding edge functionality that has not been added to master yet, checkout the bamboo builds for the development branches, currently develop-v1 and develop-v2. There are two development branches since version 1 and version 2 are being worked on simultaneously. The current policy is that develop-v1 gets merged into master on the last Wednesday of the month as development towards version 1 of Ergo/NIST-CORE continues. Sometime after version 1 gets released, develop-v1 will go away and be replaced by develop-v2 when it is more functional and will follow the same merge cycle.
The master branch should be the most stable branch of the actively developed branches; however, since there is rapid development, this may not always be the case. Depending on whether you are looking for NIST-CORE or Ergo, follow the appropriate link.
Currently, the only development branches are for Ergo since the NIST project is contributing new functionality to Ergo and the NIST branch only contains branding information. To find new features for both Ergo and NIST-CORE, follow the link for the Ergo development branch.
None yet. Release specifics will be kept under the JIRA bug trackker found here.