Time and type of questions

I really do not get it. I am trying to get ready for SAT test. I am not an English native speaker, so it is harder for me to get ready for this test. Firstly, I truly do not understand why you can not use the calculater; moreover, the limit is so short, precisely in English section. What is the purpose of this test??? Do I have more time if I am not an English native speaker??? Thank you for your answer.