CX will issue the HKG-ZRH BP and check the bags through. But you cannot use the lounge unless you go to the departure level and then cannot go to HK anymore.
You would have to be taken to the immigration office, be asked questions and have a long wait. Not sure that they will even allow you to enter HK.
Better to get to HK directly and try to get some hotel room. Then you can enjoy the city and even take a nap. Not many hotels would allow you to book a (cheap) room from 6:30am (I think CX714 arrives at 05:20) to late afternoon. Maybe you could also try to change your SIN-HKG to a later flight.