as you suspected, sunscreen sunscreen sunscreen. australia is the only place in recent memory where i tanned / burned while using spf50. thick water-resistant formulations are not the most comfortable but safest.
i adore australia and am trying to find a way to spend 2 months out of the year there. university of sydney has a physically very beautiful campus and the area is gentrifying fast fast fast. the eastern suburbs are tonier and beachier. bondi is out that way. great (long) walk from bondi to coogee beach along the coast, really beautiful. walk swim eat, walk swim eat until you get to your destination.
public transit is super and exceptionally convenient. the sydney central yha is unbelievable...rooftop pool anyone? book early if you are hosteling. my restaurant reccos are out of date. but i did have a few favorites after 2 months in glebe.