Eight ball - here's an idea - drop into your local ATC facility and ask. You said you don't know much about ATC and I'm sure it won't be an issue if you ring up and arrange a look-see at YSSY (that's where you are, yes?) Approach.
Most, if not all, ATCers are quite happy to sit down and expalin the job to people who take a genuine interest. These days, with EXTREMELY limited cross-pollenation opportunities, there is a general lack of understanding of what happens in both the cockpit and in front of the scope.
Good on you for asking the questions, and best of luck with the answers!
Cheers,
NFR.