Hi Antony,
You can open the depth stream of Astra Pro with OpenNI and use lit like normal. The color stream of Astra Pro is only accessible through the UVC (webcam) interface, which OpenNI doesn’t support. We are working on better Astra Pro color support for the Astra SDK, but it isn’t ready yet.
As for skeleton tracking, we are working on our own skeleton tracking (#1 priority right now) and will update when we can share news!