Thanks for the extensive research you've been gathering. Truthfully your chances of getting any of these diseases which are associated is multifactorial and I think the best advice to anybody would be moderation. Too much of anything whether thought to be good or bad is usually not good. So understand what has been shown to be healthy and follow recommendations. Going over what is adequate may bring about other issues which may not be pleasant.
Key is moderation with anything in life. Keep things in balance.
As far as prevention, BCPL. Prevention is the holy grail with medicine. You don't know how much scientists would like to prevent cancer and other diseases. We have eradicated polio with a lot of effort but it is still out there. And the vaccine is live though attenuated. Very difficult to prevent. We are good at suppressing and treating. But curing cancer is not a cure.. It's a temporary condition. Cancer is a game of chance. Some of us are unlucky and will be more prone. Some of us will be exposed to more radiation and likely come down with it. There's a lot of factors in play with genes environment and our activities that determine when and how we will get cancer and other diseases we are exposed to. Once we understand cancer we will probably be able to prevent other processes we aren't particularly fond of.
But for now, how can you prevent cancer? Stop your own conception.
How do you prevent nonaccidental trauma? End the human race.
In other words, prevention is extremely difficult. Stopping something from happening when there is always a likelihood of it is nearly impossible unless you take that likelihood out. So as you said, preventing motor vehicle accidents, take out the motor vehicles. Preventing death, don't get conceived.