Hey.

In order to become a judge, yes, is compulsory to do a law degree. The basic minimum  requirement for RJS is that you need to complete a Law degree from a college recognised by Bar Council of India. You can become a judge directly after completion of your Law degree by attempting the Judicial Services Papers. Each state has its own Judiciary examinations. If you clear the exam and the interview you will be directly appointed to the Lower Judiciary as a Magistrate.  Process- RJS Exam is conducted in two successive stages like Judicial Service Preliminary Examination and Judicial Service Main Examination. The Preliminary Exam is conducted in order to shortlist the candidates for the Mains Exams. The score is prelim exams is not considered at a later stage while deciding the merit. The Final merit list for selection of the judges is prepared on the basis of your total marks scored  oin the Main Exam and the Interview.

You will be able to appear in RJS after completion of the course only. But it is good if you wish to prepare from now on.  Seventy percent weightage is given to law subjects and remaining comprises Hindi and English grammar. Pay attention to language subjects too. Use the bare acts as well as course books for now. Previous year papers will help you to ascertain the pattern and level.

Best of luck