Hi @holdensylducks !! Great to meet you, and thank you very much!!
I actually believe that the Brown essay you’re referencing is what got me in. I read a lot about how the one thing that Brown really, really cares about is intellectual curiosity (willingness to learn for the sake of learning (remember this lol)). Just the fact that they have the Open Curriculum so that you can explore academically really corroborates that.
With this in mind, I wrote the essay about the passenger seat of our family car. I wrote about how when I was a kid, my dad would always ask me these interesting questions that I would never know the answer to while I was sitting in the passanger seat, and how now, when I drive that car, I ask questions to my friends sitting in the passenger seat. My takeaway from this little anecdote was that the passenger seat of our car is where I learned that it is valuable to admit that you do not know something, because that is what allows you to learn; my conclusion was that “home” for me was any place that I could admit that sometimes, I do not know. I may have explained this in a very confusing way 
so PM me if you want to see the essay. I do think it was very Brown-esque and got me in the door
As to your second question. I really picked Penn because of the location, the nanotech focus, the great social scene (which many top schools lack, I’ve heard) and because of the pre-professional vibe. Many people consider the pre-professional vibe a con of Penn, but I consider it the best opportunity for personal growth that I have. I know that it will push me to work my hardest and seek out opportunities, and I think that’s needed in the real world. A place like Brown is of course fantastic, but I think I would not have learned how to be a go-getter, and Penn really, really tecahes you that.