......help me out with those figures and tell me where to find info on DIY GSPH
If you have not already done so, read ALL 1,910 discussion in AC_Hacker's 'heat pump manifesto' thread !
99% of your technical questions will be answered there.
For the solar questions, look at those threads.
You really should look at solar first given you high energy rates in Perth area.
To assess your solar potential, research 'solar insolation' NOT installation or insulation, inSOLation - e.g.
Australian Climate Averages - Solar exposure