Firstly, welcome to Australia.
Westmead, as you would have figured out, is near Parramatta, which is kind of like Sydneys second CBD, with office buildings dotted around the centre, but not so much clustered like in the city. The streets of Parramatta are bustling in some areas, for shopping, restruants and cafes. There are good parks, and plenty of history in Parramatta, since this is a place where settlement was very early. Parramatta, is located where the Parramatta river ends (the river the harbour turns into). You can catch a rivercat to the city, going through one of the worlds best harbours, and you will see the the Sydney Opera house and the Harbour Bridge as you enter circular key, the main terminal of ferrys that leads into the city. The ferry is a very quick way to get to the city from Parramatta, and economical. You can also travel to Manly a great spot in Sydney, with one of the most famous and best beaches in Sydney. Which also has alot of shopping, cafes and restruants, but I think that you have to change at circular key to go there from Parramatta
Parramatta's focal point is the Parramatta river, with great walking trails around it.
Parramatta, is the true city centre because it is in the centre of Sydney, while the Sydney CBD is near the coast, not at the centre of the city at all.
Since Westmead is so close to Parramatta, you have a wide variety of places you can choose to live, since the abundance of public transport in the area.
BTW I do not live in Parramatta, but I like it
