I think Sydney would be great, you'd survive there. Plenty of jobs that you and your friend can get and the city has it all. But the downside is the living cost, it is pretty high, you need to rent or share an apartment in the suburbs in order to lower the living cost.
Living in the suburbs (shared expenses with your friend and/or share an apartment with others) will cost you around AU$1500 for each person, but it still depends on how do you manage your daily expenses, so it can be lower or higher. I even had a friend that managed to survive there for AU$1000/month! God knows how he did that, but eventually he did for 3 years.
Jobs there pay averagely above AU$15/hr. Once I worked there part time and they paid me AU$18/hr on weekdays and AU$24/hr on weekends.
Sydney is a beautiful place, there are plenty of sites that you can visit when you are bored with your daily routines. You'd never end up with a situation of not knowing where to go once you get bored.
It's better if you have a friend or relative that lives there, so you can ask for advices and others, such as temporary accommodation once you arrive. If you don't have any friends or relatives, I could give you one of my friends email or phone number.
If you have questions, don't hesitate on asking me. I will answer whatever questions you're going to ask if I can.
Whatever choice that you're going to take, I believe it's the best one for you, so go for it. If there is a will, I am very sure there is a way. Good luck to you both.