As a Big-4 consultant, schools that are stretches (but in range) are Kellogg, Booth, Tuck, Columbia, Sloan and Haas (choose 2 from this list). Sweet spot schools are in the top-16 range like Stern, Yale, Cornell, Duke, Darden, Ross, UCLA (choose 3-4). Safeties are schools outside the top 16. From your list you are kind of in range, although HBS and Stanford are going to be long shots - apply if you want, but just treat them as lottery tickets. If you're hoping to get into more schools, you may want to swap out those 2 schools for more schools in the top 16.
As for extras, it's never too late to "start" anything - that is, if you're doing it for its own sake. But if you start something now for the sake of a b-school resume, it's not going to amount to much; it's a few months, and you won't have a whole lot to show for it (because real achievements are usually a culmination of years of hard work and commitment).