I know that apple is yet to release Research kit for development. https://developer.apple.com/researchkit/ says will be released next month.
But http://fortune.com/2015/03/13/apple-researchkit-apps-available/ shows the apps available using research kit.
I also saw release note for Xcode 6.1, 6.2 , 6.3 , 6.4 beta but no luck.
So, am i missing something to start developing using research kit or will be happy to get reason for contradict statements in point 1 & point 2.
Research Kit is now open and can be downloaded on GitHub. Here's the guide and here are the reference docs.