B-school is absolutely for applicants such as your self. Entreprenuers in many ways have the best story to tell and definitely have good reasons for wanting to attend b-school. Schools won't look down on you simply because you didn't work for a Fortune-500. They get enough of those apps as it is.
2 -- Getting recommendations from your partners would work. You should also really consider trying to get one from a customer / client of your old company if you can't get one from your old boss or from one of the companies you do pro bono work for.
3 -- Pro bono is asbolutely considered community service and would be a great tool to use in your apps
4 -- You can't go into this process thinking that you have have nothing special to write about. We all have our own story. If you think that way, you've adopted a self-defeatist attitude and have already lost ground to the competition.
5 -- Those are all tough schools to get into without any safety schools. You should really spend some time categorizing who you really feel good about and whittle that long list down. Have you considered UCLA or USC?