I have the 19" Y spokes and can confirm that the ride is great and very comfortable. Also, I live in a cold area with less that perfect quality roads and pavement. If ride quality is your only concern between 18 and 19" I would say that you need not worry.
I am pretty sure this is normal for cars with a turbo. I believe what you are hearing is quite common of a turbo cooling down after the engine has been shut off.
What i meant by intensity was that the contrast of red lights on a black car is high. I did not mean the actual intensity of the light; I was referring to the color of the plastic. Regardless, point taken.