HI! I am still confused! I am planning to fly from NY to Shanghai stay there for 5 nights

You can stay 144 hours, you won't need a visa. The limitations are that it's a "transit" layover, so if you fly direct from NY to shanghai, you must fly out to a different county, which you are by going to Singapore.
Let your tour booking agent know that you are doing this on the 144 hour no visa entry, and do the same at the airport you fly from.
When you land in Shanghai there's a lane specifically for you to use.
And enjoy Shanghai, It's one of my favourite cities :) go to Jin Mau tower, cloud 9 bar at about 5pm and just watch the oriental pearl tower lighting up as the sun goes down. Stunning.