1- It is possible for your hubby to launch a HK$700K job in Hong Kong.
2- Working hours in HK will no doubt be longer than in OZ, with higher pressures.
2- Your hubby will take home a lot more due to lower tax rates in HK. However the quality of life is likely to be lower because of longer working hours and very high housing costs.
4- If you ever consider Singapore - I will probabaly have good offers for your hubby. Our bank, a tier-1 offshore investment bank, is aggressively expanding in Singapore. Contact me using private message.