Aside from the latest patch, the update also includes stability and performance-related improvements as well as some bug fixes. As is usually the case with OTA roll outs, it might take some time for the update notification to pop up on your device.
I don't think so, maybe we're scheduled for 2018.
Why don't you call S7 pair instead of S7 duo. I always mean finally S7 duos get an update but not :)