Government & Defence Entrance Exam

To work in Income tax department as an officer or clerk it is required that you take exams. SSC CGL and CHSL are some common entrance exams. Also, if you are willing to work as IVth class employee then IT Department releases vacancies for Drivers, PAs, etc.

There are various posts available in ONGC with most of them being technical in nature. If you think you are eligible then keep visiting this link frequently to get updates on available vacancies.
https://www.ongcindia.com/wps/wcm/connect/en/career/recruitment-notice/

Yes, of course. B.Sc in IT is a valid degree and recognised too. It is a common distance learning course provided by many institutes. So it is definitely valid.

Do you mean VDO? If it is VDO exam conducted by UPSSSC then you are eligible only if you have CCC certificate along with graduation degree.

Your eye power is quite low to be even qualified for Army Medical Test which is much more relaxable.
-6.5 means that you must habitually wear glasses and that may not be possible in Personal Training.

You don't have to apply to RAW. RAW sends out invitation to best officers in department. RAW recruiters personnel from IPS, IAS IFS, Army, etc. So you don't get to choose if you have what it takes to be a RAW agent, you will automatically be noticed and get invite for recruitment.

If you have done 12th and pursuing graduation then prepare for SSC CHSL for 12th level along with SSC CGL for graduation. Other than these, railway releases vacancies each year for both 12th and graduates. Also, each state releases its own vacancies several times a year. So it means there are several options available. Read newspaper to know about the vacancies.

It would be fine if you can manage both studies at once. Your B.Sc should help you in your IAS preparations as well. Add details about your locality and course you pursuing to get better answers. But usually most people begin their preparations in the 1st year itself.

Public Sector Undertaking (PSU), most of them recruit graduate engineers as trainees / probationary engineers every year. There is no common entrance test for that as the requirements are company specific.
Candidates who are in the final year of graduation can also apply for PSU Jobs. The eligibility criteria of PSU jobs vary from company to company.

SSC CGL syllabus is composed of Reasoning, General Science and English. To prepare for SSC CGL it is best to join a coaching to learn systematically. And solve a lot of question papers.