Livy is not "hidden". If you have started the Livy server, you can interact with its REST API from any application.
Yes. With HDP 2.5. I missed that memo. Before that was "Installed as Spark Ambari Service, not yet exposed outside of Zeppelin". The following was needed: https://github.com/hortonworks-gallery/ambari-zeppelin-service
Just to close this out as i was able to get info required. Sharing RDD and context outside of zeppelin is not supported.