You are spot on about how to hold the steering wheel. Hold it lightly and rest your thumbs on the 9 and 3 position so that you can feel the road surface without gripping the wheel tightly. Once you have confidence in what info the car is feeding back to you it becomes very natural.

The boominess in the coupe is most likely due to the car you test drove having the race exhaust fitted which does drone at certain speeds. Get the car above 90 mph and it goes away so the trick is to just drive faster smiley The alternative is not to spec the race exhaust. The Akrapovic exhaust will be silly money in relation to the overall cost of the car so unless you really want it badly I'd think long and hard about optioning it. There are some videos on YouTube of a car with it fitted and I wasn't that impressed compared to the factory race exhaust.

The wayward steering in my car has been transformed by the new front shocks which are the same as those fitted to the spider and latest coupe I believe. As you say it will still find more pronounced cambers on an uneven surface but it is much easier to make swift progress in.

The header rail issue sounds more like a case of getting used to it. Funnily enough when I take the roof off in my Dino GTS the header rail seems far closer than it does in the GT coupes but in reality it's exactly the same. It's just an illusory effect and will be the same in the 4C as the front screen is the same on both coupe and spider.

I'm glad you enjoyed the test drive. These cars really get under your skin as they are so much fun and provide an experience quite unlike anything else in the same price bracket. I can't envisage selling mine and regard it as a future classic for sure.