Hello everybody, this is my first post, I hope I am writing in the right section

My name is Luca, I am 19 and attending the last year of High School in Italy where I live. I was born in Seattle but have lived there only for three months and then never came back.
Now, I am planning to study in the US but I decided too later for 2012 class so I am trying for 2013. This means that by July I will be free to do whatever I want.
My first idea was to come back to the US, to visit my birth city and improve my English. And since I want to be a doctor, I decided that I could do some volunteer work in a hospital, which is, for a high school graduate, the closest activity to medicine.
I am planning to top colleges (Harvard, Princeton, Columbia etc.). You think that this experience (travelling and volunteer work) could help my possibilities of being accepted there?
Furthermore, I do not know anybody in Seattle so I need to find a job. My first ideas were Starbucks or stuffs like that. What do you think about this?
I hope I have been clear and someone will answer my questions! If you haven't get something ask me
Bye
Luke