Just don't fly Royal Nepal Airlines. Believe me it's the worst way to fly. I had recently been to Delhi. Sahara and Jet Airways were pretty awsome. Good food, good service, clean (unlike our usual 2 hour delay RNA's flight). You do need Passport. You need to fill out your departure and arrival slip, and it asks for your passport no. Or I guess a valid ID will do. My sister who is 13 used her school ID instead. Hope it helped.