All large flying schools are a lucky dip from the students perspective as you will get assigned and instructor and may not have the choice initially.
What I do know is they are pretty comparable to other similar size schools both in terms of cost and quality. See paragraph above.
Dont be afraid to ask for another instructor if you feel its not working as its your money ralph, but if you keep not getting on with instructors, its probably you not them.
Il answer the questions one at a time.
1: That depends on your natural ability at first, and then your will and hard work.
2. No idea. Adelaide's famous for barrels full of dead bodies so I stay well clear..
3 . Hidden costs.. Uniforms, books , test fees? Nav equipment? Get all of them yourself if you can, but they may sell their own internal stuff?
4.Cant help you there. See point 2. However generally speaking doing a course along with the flight training is intense, and you need to focus on that and only that until its done, or you will fall behind, and it will start to cost you more money. Its up to you, but although you never see the cash change hands, I can assure you , you are paying absolute TOP dollar.
You could do it for nearly half if you found a reputable regional school and pay for it yourself.
Good luck.