I am doing 3 a levels ( physics, chemistry and maths). Are these 3 subjects enough and meet the requirement for admissions or are there any different criteria or requirements? I also want to know whether scholarships depend on SAT scores or not. Is 1430 enough to get scholarships.
If you are talking about US universities, you are good. Most of the universities have lenient requirements to apply but very hard to get in.
Placement into US universities depend upon varieties of factor. Your academic prowess is just one of those factor. Yes, there are universities that provide scholarships based on your academic achievements but the amount of those scholarships tend to be low. They look into your extra curricular activities, recommendation letters, your common app essay, your family financial situation. Therefore, someone who has average grades, could have other talents that the university is interested in. Moreover, not all universities are looking for the same kind of students. They want to have students that can fit well in their environment and prosper.
The main takeaway from this is that US universities look into various factors before offering you a placements. Each of the those factors are more or less equally important.