Where is it?
The bottom of the East Coast of Australia. 
Where should I be heading for?
It depends what you're after.  Backpackers usually head to the Kings Cross Area, whereas the more swank places can be found round the Circular Quay and the Darling Harbour regions.
Entry requirements:
If you're after a working holiday then you need to request a one year visa, which enables you to undertake casual work to supplement your travels. However you are only allowed to be employed by one company for no longer than three months and it should not be work that could further your career.  This is very unfair, seeing as Aussies and Kiwis can come over here for two years and do pretty much what they wish!  If you're after just a holiday then you also need a visa, which will need to be organised before you go away (i.e. no scribbling on a coupon handed out by the air stewardess 10 minutes before you touchdown at Sydney airport!) Oh and be warned, the Australians are very strict about bringing food into the company so make sure you have eaten all your sweets on the plane, or you will be hunted out by the sniffer dogs!
Health:
If it is dangerous creatures you are after then you come to the right place.  Australia has more scary beasts than you can shake a stick at (and it is probably worth having a stick with you just in case you do come across one!)  Admittedly most of the harmful beings are mostly
found in the outback and in the Northern territory and Queensland, which has a more tropical climate, but you are not safe even in urban Sydney. Sydney (and only Sydney oddly enough) is home to the deadly funnel web spider.  There is also the possibility of sharks (although some beaches have shark nets) and then there are the blue bottle jelly fish. These are not deadly but are extremely painful and are prevalent in all of Sydney's beaches. They come in waves so there is usually a warning as soon as a lifeguard spots one.  Oh and while we're on the subject of the sea, always make sure you swim between the flags, otherwise you may get caught in a nasty rip tide, which once you're caught in, is hard to get out of.  Apart from all that though, Sydney is as safe as houses, mate!
Top 5 things to do:
1.  Circular Quay  – this is the home to the Sydney Opera House and the Sydney Harbour Bridge. No matter how often you see it on TV, it is breathtaking when you see it for the first time. If you're feeling particularly adventurous you can climb up the bridge (wearing a very attractive blue jumpsuit) or the more vertigo stricken can take a guided tour of the opera house.  Afterwards you can have a drink in one of the swanky cafes on the quayside.
2.  The beach  – OK so everyone goes on about Bondi (which is 10 minutes out of Sydney) but there are many other beautiful beaches around. Just as good as Bondi (if not better) is Manly beach in North Sydney. A 30 minute ferry ride from Circular Quay takes you there. Be warned though, Bondi and Manly are surf beaches so they cause a re-arrangement of your bikini every time a wave comes in.  There are also calm water beaches which are a short bus ride away, notably shark bay (don't worry, it has a shark net) and another one in the Vacluse area.  If you don't mind travelling on a bus for one hour you can also visit Palm beach. The name you won't recognise but the scenery you will.  This is where Home & Away is filmed and you can even have you picture taken outside the Summer Bay Surf Club.
3.  Go to a Neighbours night – these are fantastic!  Created mainly for English backpackers (though you may find a smattering of other nationalities there), these occur once every three months.  For $30 (approximately £12) you get nibbles, quizzes (with cash and other prizes) and, the best bit, three Neighbours stars!  They mingle round each table having a chat with you and let you have your photograph taken with them.  Afterwards it turns into a club.  Cheesy, I admit but a great night out.
4.  Go up the AMP Tower – this suggestion may sound mildly rude, but it is actually the tallest erection (oops again!) in Sydney. At the top you have amazing views over the city and its surrounding areas. There is also a brilliant experience included in the fee which includes a hilarious jaunt through different rooms of Aussie history and culminates in a seated
ride where you are taken on a virtual trip of Australia (much better than the Empire State building one).
5.  Shopping – there are loads of shopping malls and you can pick up cheap surfing labels (such as Quiksilver, Roxy and Billabong) as well as high street chains like Sportsgirl (the aussie equivalent of Top Shop) and Jeans West to name a couple.  There are so many more things to do in this fabulous city like visit the Botanical Gardens, which overlook Circular Quay, go to Hyde Park, go clubbing, visit Kings Cross, which as well as being home to the vast majority of backpackers, also doubles up as the red light district!  (I knew there was a point to all this! - Ed) Darling Harbour and China Town are also well worth a visit as is Fox Studios.   There is always something going on in Sydney as well, so whatever time of your year you are there, it is worth checking out the local press to see which festivals/major sporting events are taking place.
Interesting fact about Australia 1:
People often wonder why a shit hole like Canberra is the capital city of Australia instead of the more cosmopolitan Sydney. The reason is that officials could not decide between Melbourne and Sydney as the capital so instead they chose a city that was in between the two. Australia's Prime Minster shocked the Canberra residents when he became the first premier to decide to live in Sydney, instead of the traditional residency in Canberra.
Interesting fact about Australia 2: 
As you will see from above, Australia is not very inventive when it comes to names. Places are either named after the people that discovered them (which means you have lots of regions named after the same man!), a British monarch, or they are named after places in the UK.
Interesting fact about Australia 3: 
The biggest hole in the ozone area is over Australia so the rays are much harsher.
Is it expensive?
No!  The exchange rate is favourable to the pound, so everything is much cheaper than London.  Not as in Thailand or India proportions, but significant nonetheless.
What's the food like?
Much the same as over here, though I am inclined to say a bit better as it is cheaper and they have more generous portions. Even the McDonald's hamburgers seem bigger. The seafood is great and make sure you try out a kangaroo steak or an emu burger!
Is it safe to drink the water?
Yes, and make sure you drink lots of it in the summer!
What are the toilets like?
Ceramic with water in and a flush. (Smart arse! - Ed)
What to wear:
Very little in the summer, but make sure you also wear tons of sun cream. 
Best time to visit:
Summer (which remember is winter for us). Sydney does not get as hot as the other Australian cities, so it is not too unbearable.
Most overrated thing: 
Bondi - reminded me a bit of Bournemouth, actually!  Has a cool hippy vibe about it but nothing special.
(5/5)