NIMCET

Yes, you are eligible for NIMCET, because you have a graduation degree along one subject, as a computer Science.

The eligibility should be graduate with degree (BCA/B.Sc (Hons.)/B.Sc/BIT) as per 10+2+3 pattern from a recognised university to apply for NIMCET. Since you are doing B.Com., you are not eligible for the same.
Good luck.

Yes, you can get but you have to crack the JEE Mains entrance exam.

NIT colleges are the best colleges for MCA. NIT colleges ranking for MCA (you should fill in this order) NIT Tiruchirappalli (Trichy) NIT Tiruchirappalli (Trichy) The top most college for MCA in India. NIT Surathkal. NIT Warangal. MNNIT Allahabad. NIT Calicut. MANIT Bhopal. NIT Durgapur. Top MCA Colleges/Institutes: ITM University, Gwalior. Jamia Millia Islamia, New Delhi. IIT Roorkee. NIT, Surathkal. Birla Institute of Technology (BITS), Ranchi. NIT, Rourkela. PSG College of Technology, Coimbatore. Vellore Institute Of Technology, Vellore.

Yes, surely you are eligible, but you must have 60% in B.Sc in CS which you studied.

Yes, you are eligible for this higher education.

The eligibility criteria for NIMCET is as follows:
Candidates must have scored at least 60% in aggregate or 6.5 CGPA on a 10 point scale in B.Sc or B.Sc Hons or BCA or BIT of minimum 3 years full time with mathematics/ statistics/ equivalent subject as one of the subject from a recognised university. Students with BE or B.Tech/equivalent from a recognised university can also take the exam.

Yes, you are eligible for this entrance as the eligibility for B.Com is to pass in (10+2) from a recognised board or equivalent to it. Yes, a commerce student can apply for B.Com degree. You have to wait for the cutoffs and even some colleges prefer direct admission or spot counselling, so be aware for them from time to time. Good Luck.