As far as the Step II question is concerned, many people seem to have opinions on this but I'll share mine. If you did really well on step I, I think you can take step II any time you want. I do not know many people who are currently applying to more competetive fields, whose step II scores were less than their respective step Is. In my opinion, the only time a rockin' step II score is needed is if one is trying to make up for a lesser step I score. Which has been discussed at length on several occassions on this site. A good marker, in my experience and many I've spoken with, is how well you did on the NBME shelf exams. Percentile-wise, I think people do fairly comparable (considering those shelf exams are primarily retired step II questions). I only had one interview where step II came up, and then it was only to ask whether I had taken it yet because they were trying to see if I had any fun plans for the rest of the year. I took it in Dec., and in retrospect wished I had not pushed it off that far. Plus, you don't even have to report it, should you not be happy with your score. Fourth year should be more like a vacation, and by the time you're done interviewing about the last thing you may want lurking in the back of your mind is the step II requirement.
I like the thinking that some of the less intriguing subjects will still be fresh in your mind, and this can only help you on the test. The only requirement I had not completed at test time was Neuro (which worried me a little), but while my test seemed to be neuro heavy, the questions were very, very fair having only studied the neuro sections in First Aid Step II and Boards and Wards. So I think if you have a window of time in which you think you want to get it out of the way, go for it. Hope this helps. Good luck!