SAT

Hey Deep,
US admission process is holistic, nothing particular can assure you admission in US universities, they will look at your whole profile not just 12th marks but all the high school marks viz. 9th,10th,11th and 12th marks with your SAT and TOEFL marks and your ECs. So, you see this is a bit complicated process. Scoring high grades in SAT or 12th will not ensure you admission in the universities. You have to maintain your whole profile and show the university that you deserve the admission.
I hope you got me.

After completing your class 11th, you can register for TOEFL.

First, you have to register and take admission tests like SAT, ACT TOEFL or IELTS and you have to do really well in these tests, if you are particularly aiming for IVY Leagues.
You have to check the university's website, if they require SAT subject test. You can collect your class 9th, 10th, 11th and 12th grades and SOPs and LORs. The university will also look at your achievements and extra-curricular and finally you can apply to universities of your choice.

Hi Deep,
It is not possible to take SAT exam from home. You can prepare at home but you have to take the exam at the pro metric center.

Hi Kalyani,
It is not required, if you have completed your class 12th from CBSE board. If you are from state board or ICSE board, then you must take SAT.

Both of them will accept it.

Dear Mukesh,
It depends on the country. In US it does not matter which board you are from. In UK SAT is not required. Similarly, every country would have different requirements.

Dear Deep,
SAT subject tests are not compulsory at all. The highly ranked universities require subject tests in normally two subjects. Advise you to visit university websites for admission requirements.

Hi Deep,
With the new scoring system you should have at least 1300 out of 1600.

There is a publisher named Collegeboard, you can opt for those books.