I completely agree with aaaabbbbcccc1111 (I wish you had a shorter name LOL) you should strive to do your very best in all of the tests, preparing as necessary. If you are made out of the right material you will pass and if your not, its no big deal, there are plenty of other jobs out there which require a different skill set.
Yes we all want this job more than anything else, but anyone thinking that they can kid, wing or cheat their way past their selection tests, is simply kidding themselves.
I myself have Stage 3 coming up, I am so nervous its unbelievable. I will prepare for it to the best of my ability but I will not pretend to be someone I'm not. I am a genuine, hard working, consciencious and diligent worker, I love learning new techniques and am a very fast learner and I hope that I will show that to the recruiters on my stage 3, thats all I can ask for!
Good luck to anyone at whatever stage they are at!
Peace Out!