scholarships for us students and tuition difference

I am wondering if US based students can tell me how the financial scholarships works. I am confused by info I read online.
What would an unweighted 3.95/ w 4.35 gap and a 2130 SAT qualify for? Also how does need based aid work for us students?
And lastly, tuition for Business school is more than twice as much as liberal arts? can you transfer into the business school after two years to save money? Why the big difference in tuition.

There is little if any need based aid for international students.

Here are the minimum requirements for major merit scholarships, which are open to internationals:
http://www.mcgill.ca/studentaid/scholarships-aid/future-undergrads/entrance-scholarships/criteria

It is possible to transfer from say Arts to Desautels but you may not be able to complete all the requirements in 4 years.
Desautels and a few other faculties have deregulated tuition. McGill can charge what it wants without government control.