Unless you have phenomenal stats (and even if you do), I would not advise you do apply early decision. I applied ED to UPenn and I was deferred to regular decision then waitlisted. It held up my applications for a while and really discouraged me. Please talk to your pre-health advisor about this. I wanted to believe it was the best move for me but it ended up nipping me in the butt. If you were told that applying ED increases your chances of getting in, I would tend to disagree. You would be better off applying early and to a broad range of schools, but also express your greater interest in certain schools after you interview there. You can always send a letter of intent after having completed you interviews if you feel one school is the perfect fit for you. If you have any more questions, please feel free to PM me. Good luck with your decision and don't take it lightly.
And I would disagree with this statment. At my school, if you are close to the normal stats, you normally would get an interview. The last 2 years, no one who got an interview was rejected and they all got some form of scholarship. Now, my school isn't Upenn, and it's prolly different for them, but for most schools it gives you a huge advantage.