SAT

Dear Sakshi, know why SAT subjects tests are taken. 'Students typically choose which tests to take depending upon college entrance requirements for the schools to which they are planning to apply'. Therefore, you take the subjects which are related to your field of interest and to demonstrate your academic potential. Interestingly you did not mention which area of engineering. There is no minimum score for Stanford, students who are admitted are generally among the 80th or 90th percentile of test-takers. A score ranging above 720 would be safe.
Best Wishes

You can give SAT anytime, without worrying about eligibility. SAT exam does not have any specific eligibility criteria.

Dear Aarushi,
Yes, you can appear for SAT exams, irrespective of your stream. For more details, please check on the given link.
http://www.indiaeducation.net/international-exams/sat/sat-eligibility.aspx
All the very best.

Dear Risabh,
SAT is the standardized aptitude test for admissions in the universities of USA and Canada mostly. It mostly includes high school level mathematics, english and reasoning skills. TOEFL and IELTS are tests for proficiency in English language. You need to take either one of TOEFL or IELTS when you apply abroad. Every university has its own score requirements which you will find on the respective websites, For more details you must check the official websites.
https://collegereadiness.collegeboard.org/
http://www.ets.org/toefl
https://www.britishcouncil.in/exam/ielts
Regards

Please explain or elaborate your query. These are standard tests for admissions abroad, for details you must check their official websites.

I have studied abroad for my Bachelors degree and it was and is extremely expensive. Your living expenses are INR 10 lakhs per year and the tuition fee is minimum INR 10 lakhs per year. If you want to study HSC Year 12, you would have repeat 2-3 years. Hence I strongly recommend that you finish your Bachelors degree here in India with good percentage or grades. Then you may go abroad. Hope this helps. Thanks!

How can someone else tell you if you find the exam tough or easy? Its upto your strength and weak areas. Since it is the test to get into American universities it is not going to be easy else there would be no test at all.

NO!.
You should have min. 50% marks in 12th standard
and should have given JEE Mains Exam with a non zero and non negative score