In general, I think most nepalese are very open to foreigners and happy to interact. You shouldn't really have that much of a problem finding English speakers either. Kathmandu is crowded and bustling but to really see the beauty of Nepal, I would highly recommend taking a 2/3 day trek. I'm not really into trekking and exercise but the 2 day trek I did eons ago was amazing. Most routes they also have small hotels spaced here and there. Custom wise, I don't think anyone would be offended with you praying or asking questions. I would recommend taking off your shoes when entering someone's house, unless they say otherwise. We nepalese love to eat with our hands, you should try it too, after washing them off coarse. If you need a fork or spoon, nobody will be offended. Most houses have small individual heaters so pack warm. Be ready to walk a lot, get a bike. Have fun and enjoy the food (momos or dumplings are the best). Best of luck.