You have Photoshop CC 2015 because it is the current version (2015.4). CC 2016 will be released when Adobe is ready to release it. Such announcements are not made in advance.
I thought CC implied no more major releases, only continuous incremental improvement (not that I've seen a lot of that either).
I don't understand your question. Photoshop CC is the only version of Photoshop that will receive updates or upgrades. As I understand it, there will be a Photoshop CC 2016. There probably won't be a lot of changes, but the naming convention will probably be consistent. I don't work for Adobe and don't have any inside information. But that is how I understand it.