Hi Falcon,
I agree, I’d avoid the heat if possible. Also, see if you can get hold of a billy goat aerator from billy goat hire Perth - seem to be an easier machine to use, and better than the bluebird style units in my opinion. What kind of grass do you have? It will help to know what it is especially if you are doing a low mow. The eco growth products are great, I use eco wet every fortnight and eco prime purple every 4 weeks (at 24g/sqm) as part of my program. I have use emerald in the past, and will again. It is great too. I personally would remove the cores, and if you were to top dress I would use organic compost, clay etc. I would only use sand if levelling was necessary, as I’m assuming your soil is basically gutless sand down there anyway. There are some good mixes - hills organic supplies have a lawn and vegetable mix which is composted cow and sheep manure with kaolin clay in the mix. There is also stuff from green life soil, poo2you, and I’m sure there are many others.
Cheers,
John