Addition or Extension Parramtta Council

I have recently purchased a property in Northmead, NSW. Below is the floor plan (advertised by agent) and sewage diagram. I wish to get some renovation and extension done to the house before I move in.

This is my first and so I have many questions.
The Existing house has 3Br 1Bath Kitchen and living area. I want to add 2bed and a family area.

My aim is to move in as soon as possible and to expedite the completion of the extension, I am open to a detached extension with set designs routinely used for granny flats and connect both the existing house and new extension with a corridor.

Briefly my plans are to get the following done:

1. Add family area.
2. Add two bedrooms both with en-suite. – I want total 4 bedrooms plus one study
3. Renovate existing kitchen.
4. Renovate the existing bathroom and if possible, get it separated into a powder room and attach the rest to one of the bedrooms to make it en-suite.
I wanted an idea on the extension and/or modifications to existing dwelling that will be required to accommodate the above, a ballpark figure on costs and the timeframe. I know it is not possible to get a formal or close quote, but a rough estimate would give me some base to start with. I wish to move in as soon as possible.