Chemistry is a high scaler so it's very good if you get a high external mark in it. If you get a band 6 in the Chemistry external your ATAR would be in the high 90's.
Lets look at what the people say: http://www.boardofstudies.nsw.edu.au/bos_stats/pdf_doc/student-survey-report-2010.pdf
Biology ranked highest at 88% of students agreeing with the statement "The course was interesting"
Yeah, i agree about the essays but the short answers had a lot of like 2 & 3 marker questions whereas last years HSC had a lot of 4 markers & 1 each 5 & 6 marker.
Nah, we still need to do a bit of People and economic activity