Essentially, for a near-maximum ATAR, it would be reasonable to suggest that you should aim to place as high as possible within your cohort across your subjects. This is generally true regardless of the school that you attend. An example of this would be placing first across your subjects, or within the top 3 or top 5 students. However, since you attend Baulkham Hills High School, a high-ranked school, you can likely be on track towards achieving your ATAR goal without necessarily placing among the top few students. This is primarily due to the high academic capability of your cohort, which typically means that you can achieve a 99+ ATAR while being ranked slightly lower (for example, being ranked 20/100 in a particular subject). On the other hand, at a lower-ranked school, a rank such as this would lead to unfavourable performance due to a less capable cohort, hence the need to place as high as possible. Overall, you should do your best to place as high as possible, but should not stress if you are ranked slightly lower (which is possible given the competitiveness of a cohort such as yours), because that may still reflect favourable performance in a subject.
The answer to your other question is no. Generally speaking, the university where you complete a Doctor of Medicine program (or other medical programs) is not a primary factor that is considered when applying for jobs, unlike other fields, such as law, where there is greater emphasis on the specific university that a graduate attended, alongside other factors such as academic achievement and relevant experience.
I hope this helps!
