<p>There is only one difference between ED I and ED II: ED I applications are due November 15; ED II applications are due December 20. ED I is generally said to provide the best chance of acceptance, although that’s also said about Early Decision applicants in general. I have no way to answer your third question, although I applied ED I and was accepted with an average GPA and mildly impressive SAT scores. But clearly you should always take anecdotal evidence with a grain of salt.</p>