Buck has pretty much summed it up, but here are some of my thoughts...
There are Pros and Cons of each method- one large tank divided or individual nano tanks.
It really is up to your preference and future plans, and budget.
I like individual tanks personally since I keep Cherries and CRS/CBS, which have different water parameter requirements. That way one tank can be tailored to cherries, and another tank can be tailored to CRS, and yet another tank can be tailored specifically to tigers. I also like the idea that any outbreak in disease is contained to the one tank only.
But there doesn't seem to be a right way or wrong way, nor even one that might be significantly better than the other. Both methods can work, as proven by many people.
As for filtration - if you choose the 'one large tank divided into sections' route, then add a canister filter. Overfiltration is never a bad thing, especially in small nano tanks where you don't have as much volume of water.
Heating is not too critical in Sydney. If you have one tank divided, then one heater will be sufficient near the outlet of that canister mentioned above. The heated water will be pushed to the other sections. Any brand of heater will be sufficient, as long as you trust the brand.
As mentioned heating is not too critical, however it is the heat of summer that is the bigger issue. My cherries in my garage survives our Sydney winter. You will need to look into chilling eventually. One chiller to chill one tank is already expensive. Let alone 2, 3, 4 or 5 tanks. This is the point where it becomes the deciding factor for many shrimp keepers. Buy one chiller to chill a larger tank divided into several sections is going to cost less than buying several chillers to chill many tanks. Considering chillers can cost $400+ each, it becomes a no brainer.
Lastly my thoughts on substrate. As mentioned by Buck, inert substrate is fine for cherries. But at pH7.8 water, it doesn't hurt to use a little plant substrate to reduce that to a more neutral pH7.0. You probably only need a very thin layer to reduce the pH from 7.8.
The best substrates (that we can easily get in Aus) to use would be Cal Labs Black Earth Premium, Benibachi soil, or ADA Amazonia. Proper cycling of the new tank with these substrates need to be observed.