It sounds like a great trip! I suggest that your first priority is a top quality tripod and ballhead. Expect to spend $1000 and it will last a lifetime. It will help your landscape and wildlife photography. The next addition would be the 300mm f/2.8 lens and the TC 2.0 III extender. You then have a 600mm f/5.6 lens. Then, if you still have the budget, buy either a D800 or D600. Since I moved from DX to FX last year, I can attest that it is an expensive transition if you buy the FX lenses. I'd recommend the 14-24 and 24-70. On an FX camera, the 105mm and the 70-200 really work great. For wildlife, DX works great with long glass. You may find that having two cameras is best, one DX and one FX. There will be less lens changes in the field.
The other issues is managing all your images in the field over a year. How do you store and duplicate them?
John Herrel Nikonian from South Carolina See the light, capture the essence!