if you go high up in the mountains, there are a few (obvious) things to note:
1) There is limited mains power (220V), so recharging batteries can be problematic
2) Because of low temperatures, battery life is shortened
3) the light can be very bright, even at iso 100, 1/8000 and F18 I had over exposed images, so take ND and circa Pol filter, if you can afford, take a big stopper.
4) Nepali people are extremely friendly and will be very interested in your gear, so take time to explain
5) If you can find it, take an old fashioned Polaroid camera and give the pictures to the local people, they will be extremely gratefull
6) Nepali will treat you with great respect, please return the favour
7) The average Nepali wage is very low, a school teacher earns about 800$/year
Hope this helps a bit,
I have been to Nepal many times and it has become a second home, I am sure that you will have the time of your life!