Hello there Bsouth,
As I see it you need someone who is personally interested in your projects, not just a "professional" blogger. I believe I could be that person. I am training to teach children English and am very much interested in social change.
You'd like to hire a native speaker with excellent English - I can offer that to you at the lower end of your price range - a dollar here in Latvia goes a lot further than in the States.
I would gladly do research and write for your blog, with a few caveats. It seems like you are looking for both a writer and an advertiser/promoter. I would take on those responsibilities with pleasure - I participate actively on Facebook, Google+ and know the workings of Twitter, but 3 hours a week to both research, write+format a post and then promote it is a tight squeeze.
You might get someone to do that, but not in a very quality way. Regardless, I would gladly do a trial run of a week or two for you, in which time you could decide if you would like to keep me on or not.
I'm new to Freelancer, but just completed my first assignment and received glowing feedback.
I hope you'll take things into consideration and choose me for your project. Attached to my private message to you you'll find a quick article that I wrote about freeganism.
Best wishes,
Mihail