A good camera is a must, Nepal will stay in your memory forever but your photograph collection will be your Nepal.
I used :-
I used a large bum bag whilst on trek, the telephoto lens fitted in (just) alongside my travellers cheques, cash, guide book, notebook, etc.
The telephoto proved useful for mountain summits, wildlife and taking pictures of local people going about their daily lives. A wide angle lens is very necessary - the mountains are so big!
It is very bright up in the mountains so make sure that any film that you take is fast enough for your camera to cope with the amount of light, mine has shutter speeds of upto 1/2000th of a second and I'm sure that some of my photographs were taken on this limit. Also make sure you take spare batteries, especially if your camera is all electric, the cold can affect battery power.
If you live in the U.K. I suggest that you have your photographs developed at Boots who did a superb job on mine. I bought my film from MX2 who charge a fraction of High Street prices.
The photographs on this web site were all taken by yours truly. They have been scanned at 150dpi on a Mustec ScanExpress 12000p and manipulated by imaging software to fit on the web pages.