Railways

Indian Railways fill their class I officers requirement by Indian Engineering Services examination, SCRA or promotion of class Ii officer to class I based on performance and experience. Unfortunately CSE is not a subject in Engineering Services Examination conducted by UPSC and you are not eligible for SCRA (it is after 12th). You may have to appear in Electronics paper in IES to become qualified to join Indian Railways. You can appear on Class II railway officer's job advertised regularly by RRB (Railway Recruitment Boards).

You need to have a graduation degree to be eligible for the job. Also, he/she should have basic knowledge of Computer. Also, you must be able to speak read and write the local language for the location you are applying.
The selection is done through examination conducted by Railway recruitment board (RRB).

Defense Services and Railways require an equal number of Mechanical and ECE engineers. You may choose any branch as per your interest to excel in professional life.

Yes, you can apply for all the general competition exam as you are done with your graduation degree you can apply for exam either by online mode or via written mode.

You have to continue your intermediate studies and stay updated with the official website of Indian Railway for jobs on vacant seat for class 10th level candidate.

You should continue your studies in class 12th standard and stay updated with the official website of Railway for job after class 10th qualified students.

Yes,
There are a few entrance exams in railway which needs to be cleared that will get you to work in railways.