Exactly! This is how the program works, if you don't want to try and scroll through the website:
Stage 1: Students are selected by their schools to sit the NQEs (National Qualifying Examinations) in physics, chemistry and biology
Students are generally in year 11, but it's certainly possible to sit it in year 10. Most schools heavily restrict the number of students taking the examinations - they're pitched at a level so that only the top 2 or so in an average sized cohort really have a chance at answering more than a handful of questions.
Stage 2: The NQE
These are in around August, and test the concepts underpinning the sciences. A large amount of preparation is recommended for chemistry though - the whole multiple choice section tests knowledge, not reasoning skills. It's also recommended to try and do a few practice problems beforehand to get into the right zone of thinking - the thought processes required differ dramatically from VCE - there's a lot of first principles.
Certificates of High Distinction, Distinction, Credit and Participation are awarded after the NQE. The top 24 or so students across Australia in each science are then invited to participate in the summer school.
Stage 3: The Summer School
2.5 weeks at Monash in January, with around 13 hours of science a day. Students cover approximately the first year university course of their chosen discipline (with many programs extending beyond this), participating in labs and sitting examinations. Students then have about 6 weeks before the Final Selection Exam (FSE), which is used to select the national teams.
Trust me. It's hard.
Stage 4: The teams
The teams then attend another training program at Monash in April, before heading off across the globe to compete in the international biology olympiad (IBO), the international chemistry olympiad (IChO) and the international physics olympiad (IPhO). Physics usually participates in the Asian Pacific Physics Olympiad too.