Well then, welcome to Aussie mate
I'd have to say, you've just gotten yourself quite a lot of work to deal with once you get to Sydney. The main problem with newcomers is often housing - rentals in this city is the highest in all of Australia (expect to pay around AUS500-AUS700 A WEEK for a decent two-room, one bathroom unit with garage space), and be mindful that competition for an available unit is FIERCE (you MUST be at the inspection on time).
Unless you really have to, do NOT try to get a car or live out in the suburbs, the congestion will sap the life out of you. Try to get used to the bus and trains as well, they run relatively on time (comparable with Singapore and Washington DC, minus the union strikes). Work visa permits for are relatively easy to get as well, especially if you're proficient in the English language. Just ask my Benoni classmate - yeaps, she's from South Africa as well, you wanna come over for some braai with her next time?
As for entertainment, not so much for Darling Harbour and other touristy areas clsoe to the Opera House - the food is too expensive and the shopping is kinda tacky. George Street in the CBD houses high-end stuff (Armani, Apple, etc.) and Chinatown has a lot of pubs to get down and personal with cheap beer. Gay life in this city is strictly concentrated around the Australia-famous Oxford Street in Darlinghurst (just go to Hyde Park, walk along Liverpool St away from the city centre and you'll see it). If you want to see the more eccentric side of Sydney, head down to Newtown IMO (take the train from Central to Newtown station, only 5km away), especially on the weekends. The inner city neighbourhoods of Glebe and Balmain is good for its diverse cuisine and retro stuff.
I myself am still in first year uni, and I've learned so much from just 18 months of spending time here in Australia. Trust me, if the weather, food, beaches, amazing nightlife and eye candy - just go watch a Friday night footy game (National Rugby League), you'll know exactly what I mean by eye candy - doesn't do you justice, I don't know what will.