1) To tell you the truth, I really haven't looked into the whole metabolic damage thing, but I'm interested in educating myself on it, as I think I should considering I work in nutrition. I remember Scott Abel talked about it at length for years on his blog and in his magazine articles. If I recall correctly, the subjects in the famous Minnesota Starvation Experiment suffered from what is metabolic damage even after being rehabilitated, like obsession with food, hypochondriasis, edema in the extremities, decreased libido, depression, and a lowered BMR. I think you can screw up your metabolism or how you store fat because of extreme dieting, whether it be chronic over eating or yo-yo dieting or some of the semi-starvation diets that some prep coaches give their clients. I have areas on me that would probably take severe dieting to get rid of, such as the "love handles" and lower back because of permabulking for too long in the past.
I believe generally that it comes down to total caloric amount and adequate protein and EFA and micronutrient amount. Again, as I said above, it also comes down to what someone can stick with. Some people, like myself, love savory, fatty, greasy foods while others crave carbs and would rather have a lower fat diet. What people like more might not make things ideal, but compliance matters, except during a contest prep in which LIKING something has nothing to do with stepping onstage at 5-7% bodyfat, but rather what WORKS.
There is some research dealing with people who utilize fats or carbs better and what would be more suitable for individual cases.
I wrote a thesis comparing low fat, high carb diets versus higher fat, lower carb diets in endurance performance in which I compared 20 something studies and I couldn't come up with a conclusion as to which was better because subjects in all studies, once they adapted to higher fat diets, functioned fine, whether they were elite athletes or recreational exercisers. In all the studies, respiratory gases were collected to show the subjects had actually adapted to higher fat diets.
I believe that nutrient timing has become a bit over involved. No, I don't think someone has to taper their carbs as the day goes on or that you can't eat carbs at night or that there has to be some particular nutrient combining like P and F or P and C, but I do think adequate nutrition around and after a workout is critical.