yes....you are screwed...UNLUCKEH!!
nah but seriously you will do good, "A man who has done their best has done enough". 75+ ATAR is what im thinking, remember its a percentile which technically means your ranks are important :)
good luck with your exams..
Depends what kind of student you are. I do both so i can tell you that business is all memory and regurgitation of information while legal is more analytical and based on the evaluate questions.
Personally i prefer legal because i want to do it as a profession.