$20k last year. it was $30k in the 17/18 tax year (but up to 75% of the tax due, not 100% like last year)
as for the 2 weeks per month HK, if you are in HK fo r >60 days each tax year you fall within the scope of HK tax.
If you are in Australia permanently with trips out of Australia, on the assumption that you are or become an Aussie tax resident you would also be required to be subject to PAYG +super on your monthly income. if you end up being double taxed you will need to pay HK tax on your HK workdays and claim a foreign tax credit on the aussie side to relieve double tax.
My 2 cents is that you engage an accountant on this. If you are changing your work location, you should also be getting some sort of Australian employment contract. technically the australia corporate entity would have a requirement to file employer return forms to the HK IRD. In addition by being in HK on a recurring basis for a relatively long time you are exposiing the australian entity to corporate tax risk in HK by way of permanent establishment risk.
So I suppose my point is that your situation is more complicated than your boss approving this arrangement. There are local and cross border corporate and personal taxes at play here.
Final point on compliance is to make sure you have the right to work in both locations (ie work visas etc).