The Google Camera version contained in the Android N preview is now available in Play Store with the features you are already familiar with.
The Google Camera is v3.2 and includes all the changes you desired and must have read about already, including the ability to take a photos while recording video. There’s a new slow-motion mode which is common in some Nexus phone. Note that not all new features are available on all Nexuses.
When shooting in HDR Mode will hopefully performed the same increase of speed found in the Android N preview 2. What used to be a unpleasant long wait while HDR did its thing has now become a endurable experience.
You can find the newest version of Google Camera on Google Play Store, Download from the link below.