How do I send transit permit requests to carrier?

Hi,

I hold USA passport. I plan to arrive Shanghai on May 20th from Tokyo, have some meeting in Shanghai with our local employees and leave on May 21st for Taipei. I would like to confirm that I can use the 72 hour free transit?

There is a paragraph on "they should make sure put forward transit permit requests to the carrier airlines in advance, so that the airlines can declare it to the airport customs before landing.". I plan to take ANA flight from Haneda to Hongqiao. Do I need to inform ANA prior to my check in on May 20th?

Finally, if I arrive on Hongquiao, then I have to leave on Hongqyiao and not from Pugong?

Thank you for your help.