I would absolutely elevate those issues to your regional zone office. You paid good money for that vehicle and you deserve to have a quality vehicle in your garage every night -- one that doesn't rattle or vibrate or squeak. Once again, there's a mentality here that if something like this fails on a domestic, it's poor quality and engineering. But on a Nissan, we'll forgive them and give them a few model years to get the bugs out. Puleeze...
We've had many first year run vehicles in our lifetime (which have all been domestics by the way) and they've given incredible service. I wouldn't expect more or less from a Japanese brand. Everybody makes mistakes -- anomolies from the factory (like the mis-aimed headlight) can be forgiven with a quick readjustment at the dealership. Excuses like, "oh, those rails banging around are normal" are unsat, and I'd absolutely kick it up a notch if you can't get satisfaction from your dealership.