Welcome to PC. This is a great place to connect with others who have panic/anxiety etc issues. You mention many "brushes" with death as a child and as an adult - do you mean you experienced loses of loved ones , or that you were literally in situations that nearly caused your death? Many people dont like to deal with death, but its part of the life cycle. I surely cannot answer why you have this issue, but just knowing you are not alone might help ! I realize it causes you anxiety to think about death, however, it seems it might also be part of obsessive thinking.

As for the #2 issue - no one is perfect, and to strive for such is setting ourselves up for failure 100% of the time. Growing up in an environment where nothing was acceptable except A's, being the best , the fastest, the prettiest, etc etc etc, is so harmful. It is definitely on the list of things identified as a reason why some people develop panic and anxiety disorder. (Plus, it sure sounds like you are Type A Personality, which increases ones anxiety levels). In your case - this is a learned behavior. You learned from your parents that nothing less than perfect was acceptable, and the trick here, is anything we learn, we can unlearn. You can unlearn this behavior by telling yourself you will do your best, you are a good student, you are answering to no one but yourself etc. "Stinkin thinkin" plays a huge roll in our anxiety levels, and its OUR thoughts that are the culprit. Therefore, if we can change our thoughts, it will get better !
#3 you are already helping yourself overcome by living in a city. Great accomplishment! You are desensitizing yourself by being in a city, and the more you are there, the more you deal with the everyday issues - people, noise etc, the less you should even notice it .

Have you considered seeing a counselor at school about these issues, or a therapist? There are also great books to help us, the best in my opinion is "Anxiety, Phobias and Panic - Taking Charge and Conquering Fear" by Reneau Z. Peurifoy. Good luck, and hope you keep us posted on how you are doing!