Will i need a visa or can i use the options 72 hours/144 hours free transit

Hi,

If i am to travel from Singapore to shanghai on the 27th Feb arriving at 930pm and then leave Shanghai on 2nd to either head back to Sydney would i qualify for a 72 hour?

If i was to instead travel to Hong Kong on either evening of 1st or 2nd March departing 2nd (so 1 day) would either need a visa or would this still be counted as part of the same visit to China?