You are a little confused brother regarding these terms. IIT is not something that you choose to do but its a college or an instituition from which students do their BTECH or MTECH courses. For reaching there, you need to go through JEE MAINS and then JEE ADVANCE entrance examinations. They are tough and theres a lot of competition for the same as well. Yes ofcourse after 10th you get two years to prepare for the exam and the exam includes syllabus of 11 and 12th standard Physics, Chemistry and Maths.

Best wishes. Thankyou.