Question about transit Visa

I have a question and request your clarification on if I require a transit G or not?

I am an Indian Citizen living in US on H1B entry permit.
I am flying with China Eastern Airline from Chicago to Delhi with 1 stop in Shanghai (Pudong) having 19 hr layover (Chicago--Shanghai--Delhi) .
Please confirm if I would need transit g considering
Case 1: I don't leave the airport?
Case 2: I don't leave the airport but there is a terminal change.
Case 3: I leave the airport and tour the city and return back to the airport with less than 24 hours?
If I require pre-approved VISA, does your 24-hour Direct Transit policy not applicable to Indian national? Can I not get on arrival temporary stay for the 24-hour twov under this policy?

Reading your article above it means we can get a temporary stay and it's upto Immigration officer. Can you please give any reference to China Embassy official site?