WDS and Unattended queries/clarification (Server 2012)

Hi Folks

I am studying for my 70-411 exam and have a few points that I would like clarification on relating to unattended installations and WDS:

1: When you create an unattend.xml for the 'Windows Deployment Services client’,  in SIM which image do you need to base this on? Do you just use the install.wim from the server iso?

2: Are both a WDSClientUnattend and a ClientUnattend mandatory for unattended to work? For example if you only want to automate the image settings but not the settings pre-image selection (such as usename/password to connect to WDS) can you specify only a ClientUnattend?

3: Can disk partitions be set in the ClientUnattend or do these have to be in the WDSClientUnattend file?

Thanks in advance.