Long Trip in South America!_Lens for NEX6 & Back up Camera?

Hi guys,

This week I got a nex 6. This coming summer, I plan to travel in South America for 2-3 months. Here I have 3 questions:

1. Bird watching will be a big issue in Galapagos and Amazon. Should I take Sony 55-210mm 4.5-6.3 or Tamron 18-200mm lens?

2. I am more interested in photographing the landscapes rather than people. Besides the 16-50 PZ with NEX 6, how about taking Sigma 19mm 2.8 or Sigma 30mm 2.8 ?

3. Any a back up camera good for multiple uses? What I will do in the trip like bird watching, diving and trekking. I prefer a 30-50x optical zoom camera or a water/freeze/shock proof camera. Which is better? Actually, it's my first time to travel alone over one month and in South America. I need your help! Thanks!

The E-mount lens I have now:

Sigma 19mm 2.8
Sigma 30mm 2.8
Sony 16-50mm 3.5-5.6

Sony 16mm 2.8

It's hard to know what will really happen during such long time.

However, the bottom line is the lighter, the better...:-P

Thanks!!!!!!