Great questions -- you're right leadership is the major characteristic that schools look for.
Schools are receptive to leadership examples from all walks. What you've described sound like terrific examples that should go over well.
I also think talking about your desire to move into leadership positions post-MBA and how you're currently restricted will also go over well. Don't be afraid to even mention that it's your interest in obtaining a leadership position and that you're not even interested in the salary. Schools will be impressed with that commitment to leadership. Just make sure what ever your chosen career path is synchs with your leadership messaging.