Showing return flight tickets for chinese tourist visa in Nepal

Hi, I'm a Ugandan citizen who will be travelling to India and then on to Nepal in January 2017. When i tried to apply for a chinese tourist visa in my home country they kept asking for a Letter of Duly Authorized Unit which I was unable to get. I've heard its much more straightforward to get a tourist visa for China from Nepal. So I wanted to ask the following questions:
1. Is it OK to show return flight tickets from Kampala (Uganda) to Shanghai when applying for a chinese tourist visa in Nepal? Or does the flight have to be a return flight from Nepal?
2. I am thinking of applying for a 15 day visa on arrival in Nepal so if I submit this to the chinese embassy in Kathmandu will it create a problem as im hoping to travel to china at the end of April 2017 from Uganda (assuming i will get a single entry visa for china valid 90 days from issue).
3. Do the hotel bookings and itinerary have to be fixed or can i change my plans once I enter China?
4. Will the immigration authorities in Shanghai give me any problems as to why my visa was issues in Nepal when my ticket shows I have flown in from Kampala?

Thanks for your time!