I'm glad you came out of lurkdom
1) How do you all do it? Are scholarships common / difficult to obtain? Do you pay from savings or take out a loan? I'm pretty debt-adverse and I'm still wrapping my head around how to finance all this.
2) How good are my chances of being admitted to a top tier MBA program with a good financial aid package?
I find it easier to address your two questions together. While most people do finance their MBAs via a combination of savings and loans (with an emphasis on the loans), the fact that you've identified yourself as debt averse might mean that it's not a good route for you to take. As a previous poster mentioned, we can provide much better feedback if we have an idea of what you want to do after the MBA.
If you are single, like to travel, and are targeting a position with the Big 3 in MC, I'd probably encourage you to pursue the best program you can get admitted to and put a plan in place to pay off the loans within 3 years or so.
If you want to work in environmental policy, continue with significant volunteer work, or go into government, I would recommend you submit applications at programs ranked 20 - 40, which will provide you with plenty of opportunities upon graduation, but that you are much more likely to receive scholarships from.
I do think you have a great profile, and would expect you to have a good shot at a partial/full ride from a program like Duke, Kelley, or Darden. You'll just have to evaluate which program(s) will best get you to your post-MBA goals, and decide how much you're willing to borrow to get there.
Good luck with your apps!