My fellow classmate seems to be coming across a bit brusque in response to your questions
@meOWzas (unintentionally, I'm sure!)... I didn't get the impression that you were searching for "bonus points"! To give you slightly warmer responses:
1) If you want to mention what you are doing in your gap year, do (this applies to you too @MDhopeful324)! I applied having 6 months of a 1.5-year gap under my belt and about to embark on the remaining 12 months. In this prompt, I included a few lines for what I'd done since graduating (which, like you, included taking the dreaded MCAT), and a few lines stating what I would be doing with the rest of my gap year. The people reading your application just want to know what you're doing with your time off, and unless you want to wait and leave it as a surprise for interviews, I don't see any harm in including future information so long as it is fixed (i.e. don't include anything that you haven't 100% committed to).
2) I wouldn't include this information in the optional prompt unless your reason is deeply personal and related to your family background/childhood. The recentness of your decision would be something you could bring up in your interview if you are given one, however! Also, in your primary essay, I'm sure you mentioned how you came to want to pursue a career in medicine -- my guess is that you implied a recent decision without explicitly stating it, anyway.
With the second prompt, I want to make a quick note that it does not
always have to be used in the traditional sense (i.e. difficult childhood, underrepresented minority, etc.). I used this prompt to describe an aspect of my identity that relates to one of my specific interests in medicine and the population that I hope to serve in the future. One of my MD interviewers actually commented on it in a positive way. So while it is true that you can definitely do harm with this essay if you come across as whiny or grasping at straws, if there is something about yourself that relates to your interest in medicine and you want to share it, do!