They did introduce the Exhaust noise generator thingy me jig between years - , it was around April 2015, So worth checking if it has it or not on a 2015 car. You will know as there are a number of additional microphones in the ceiling. All it does it take cabin noise, play with it and inject the exhaust sound over the Stereo. Somewhere on here you will find the explanantion for it. Most new members I suspect don't even know they have it. You cannot switch it off.
3 Blanks are indeed not needed by the Nismo - although some have taken it out and put in wireless charging or just a storage.
There are four colours, White, Red, Black and Silver. If the V1 had been available in Red in the UK I think I may have been thrown, however, Storm White looks amazing on a sunny day. Every owner of the relevant colour will tell you its the best, its a personal choice. But clearly White is the fastest colour
Many of us have come through the 350z to the 370z - so have about 10 years ownership or more. They are very different cars, extremely reliable in most part and can be used as a daily car. But you have to be ready to talk to people and thank them for telling you they like your car (nearly a daily event).
I have never owned a car I love as much as the Zed - it makes me smile every day, Good luck with the puchase.