Re: Nepal: My overall impression of Nepal was of an amazingly beautiful mountainous country and a very friendly/smiley/wonderful people. Also Nepal clearly still has a lot of the original culture and felt very safe. A wonderful place to go trekking in. A gem! Also for me, the mountains and people embodied something spiritual.
Re: Treks: I found that I like walking reasonably actively/speedily but that I very much like stopping when I meet something interesting - a beautiful spot to meditate, or people to speak to or a temple to visit.
Seems to me there are at least 3 types of walkers - those that travel fast, stop little, and probably will go as high as they can.
Those that would like to walk up to whatever height, but also like to stop look and listen (bit like me).
Those that would enjoy the lovely scenery and people up to about 3000m (after is colder and altitude).
Re: Charity work: Meet the people on a real face to face level, learn something about yourself and make a difference.