Uk -> Shanghai -> Taipei -> Hong Kong -> UK

Hi,
Being a UK passport holder, does this qualify for the 72 hour free transit?
Also do you have to leave before the 72 hrs is up? So say our flight arrives on Monday at 09.25, do we need to leave by Thursday 09.25 or do we have that day to fly out?
Lastly, are there any restrictions going back to HK for any length of time? Ideally, 3 nights Shaghai, 4 nights Taipei and 4 nights Honk Kong.
Thanks