My two cents is that 1) it's a great idea to go with the 7D instead of the 60D for those countries as the 7D is more rugged and weatherproofed!
As far as lenses, how about these three: Tamron 17-50mm f/2.8 non-VC (the VC version is more expensive and optically crappy), the 70-200mm f/4 (IS or non-IS, your choice) and some prime in the middle.... like you mentioned: the Canon 50mm f/1.4 or maybe the 85mm f/1.8. Also bring one flash with you.. preferably a 580EXII but a 430EXII could work instead. You probably won't use the flash much.. but I'd bring it. If you do have it in the budget for a fourth lens (and only in such a case) then I would suggest a SUPER wide for the 7D, though the Canon is expensive and not the best. I'd opt for the Tokina 11-16mm f/2.8 which I used to own and is nice, or the rather new Sigma 10-20 f/3.5. That lens looks nice!!! I've heard good things. Let us know what you go with?