Company Secretaryship

Post graduate courses in securities management, quantitative finance, risk and treasury management and capital markets are all available in National Institute of Securities Markets (NISM).
Similar courses are also dispensed by CCGRT (Mumbai). On the same note, certifications and licenses are also given by BSE and NSE relating to compliance's.
You can always go for another undergrad degree or a Masters degree. For instance, student who have done B. Com enroll for M. Com or LLB, or the ones who have completed LLB enroll for LLM.

No, if you are pretty confident about your preparation but coaching will definitely help you.

B.Com (Honors) from a good college with good teaching faculty is the best degree course for CA aspirants as it will help you in your CA preparations.

Institute of Company Secretaries of India (ICSI), Nagpur.

If you are already a commerce graduate then there is no point on doing B.Com corporate secretaryship. For those pursuing a CS course there is no special job available for those doing corporate secretaryship. Yes, from knowledge gaining point of view, you may think about it.

Yes, CS is a very good option for you but in CS you are going to study company law so think before choosing a course among CS, CA and CMA.

No, the gap will not effect your studies. You can prepare for CS and then along with that, you may pursue M.Com.

Sorry but with only 62 marks in mains, no college is available for you to give you admission.
However there is a way, you can contact private college/university.