PS if you had cash enough now you could bulldoze the lot and double that idea now to get 4 straight away.
Put a driveway up the middle of the block and one each side put 1 house and 1 granny flat.
If you really wanted to you leave a 200sqm 'block' vacant for a future 5th. Just use it as...
Yes to all. It's just a little house.
Building a 3 x 2 and a 2 x 1 or 2 x 2 granny flat at the same time will cost around $300-330k turnkey for both.
Imagine you are building a duplex behind each other but the rear duplex is just smaller.
Forward looking strategy you need to think...
Do you want to hold all or sell?
I would consider.......
Subdivide now and on the new 450sqm section build a small 3 x 2 and a 2 x 2 granny flat
HOWEVER make it so that the granny flat is independant and when zoning goes through then you could put it on it's own title and that block becomes...