Recommendations for handheld documentary/social/street/photojournalism? + OM-D E-M5 or GH3

In response to a suggestion to post in this forum rather than beginner questions:

I am embarking on a year-long trip to Ecuador in a few weeks and need advice. I am pursuing photography and video that falls somewhere within documentary, social, street, and photojournalism (interest being social issues and human rights advocacy). With this intent, I am expecting my needs are having light gear that is also somewhat rugged, carrying as little gear as possible, and using gear that allows me to be as discreet as possible. Video is also very important to me, so I’m attempting to being able to capture the best quality video with room to grow without sacrificing the other factors. Finally, my funds are what I have been able to save and I have no clients or income from what work I will produce at this point (hoping that will change). So to be clear, I am a beginner starting with zero but aiming to eventually do professional work.

Unless you can convince me otherwise , I am not interested in a camera system that relies on mirrors. I think mirrors are on their way out and starting new, I want to invest in a mirrorless system if it’s feasible. Under these needs, I am considering either the Sony NEX system or the Micro Four Thirds system as each involves mirrorless cameras that in various degrees embrace video. From there, I am leaning towards the Micro Four Thirds system for its lens selection, and for rugged reasons, I am leaning towards either the Olympus OM-D E-M5 or Panasonic GH3. And that’s where I get stuck.

A significant question I have is what focal range should I cover for my type of photography and video? I imagine a standard zoom lens would be best, but do I need a telephoto reach too? A wide-angle?

Also, is image stabilization important for this kind of photography/video? I anticipate doing most of my work handheld, in uncontrolled and various lighting, and handheld video seems to require stabilization.

I’m also undecided if I need weather sealed lenses.

I feel that these three questions determine which camera body and lenses I need:

• If I need more than a standard zoom, I’ll need either a super zoom lens or more than one lens.
• If I need image stabilization, I can use the OM-D E-M5 with any lens or I need lenses with stabilization for the GH3.
• If I need weather sealed lenses, then my affordable options are Olympus lenses without image stabilization, or use the GH3 without image stabilization, or afford 1 lens for the GH3 with image stabilization?

Also, where can one get their hands on Micro Four Third bodies (I'm in the Pittsburgh area). All the stores I've been to (big box like Best Buy) only have Canon, Nikon, and Sony bodies

So here is where my mind is, I appreciate any advice and guidance.