Government & Defence Entrance Exam

It is not necessary at all. CLAT is just to take admission in a Law Degree/Law College. To appear in the civil services or you say IAS you need to be a graduate in any stream.

The IBPS released the notification for the exam in the July-August month. There is enough time to prepare for the exam. As you asked about the percentage, there is no limitation of the required percentage. You can appear for the exam if you have completed the graduation degree. It does not matters what is your percentage.
Your age should be between 20 to 30 years old.
If you fulfill the age limit criteria then you can apply for the IBPS exams in 2018.
Know more about IBPS PO results for the prelims exam held in October month.
https://scoop.eduncle.com/ibps-po-results-cut-off-marks-for-prelims-mains-exam

It does not matter much. The minimum eligibility for taking up the Civil Service examination is a pass percentage in graduation.
So, the message is loud and clear from UPSC's side that 'It does not matter to me who you were, what matters is only who you are and who you are going to be.'
See there might be 100 reasons for anyone to be scoring low in their school and college years. It might be economic, social or personal reasons. But I sincerely feel that this shouldn't weigh a person down in his UPSC preparation.

There are some exams conducted by ISRO to get a job in the institution. You need to have minimum qualification to be eligible for the exam. And after clearing the exam and all the selection process, you will be selected as a scientist in the institute.
The ISRO released notifications time to time to select the candidates for scientists posts, Eligible candidates can apply for the exam.Tthe minimum eligibility to appear for the exam is graduation degree or higher degree. Please check the official notification for more details.

Hello,
The vacancies arising in Indian Railways are filled by the Railway Recruitment Board (RRB). Railway Ticket Checker is one of the posts offered by the railways. The selection will be based on a written test followed by an interview. The job profile of a ticket checker includes checking passenger tickets, checking platform tickets and levying fine from passengers travelling without tickets.