BCA

Yes, you are eligible for Karnatka PGCET exam, as you are already appearing your graduation.

Visit the link given below to get previous year's questions.
https://www.techbrhindi.com/2018/01/mdu-bca-last-year-questions-papers-free.html?m=1
Good Luck.

Selection is based purely on the merit of the qualifying examination and also on the availability of seats.
Good luck!

Yes, it is very important, as BCA requires regular guidance they provide knowledge about it. It will be beneficial for you to attend the classes, it will help in your future.

You can do both at a time, but there will be no benefit of doing two courses together, as you can't represent yourself at places at a time. It can be a case of duplicacy, as how a person can be present at two different places at a time.

The link mentioned here of UEM Kolkata will give you the clear picture of the college and courses with placements which will help you to decide the best college for you https://www.shiksha.com/it-software/course/bachelor-of-computer-applications-university-of-engineering-and-management-kolkata-rajar

Yes, you are eligible to apply for the NIMCET exam. Kindly check the NIMCET Eligibility Criteria 2018
Candidates must be Indian nationals. They should be graduation degree holders (BCA/B.Sc (Hons. )/B.Sc/BIT) as per 10+2+3 pattern from a recognised university. Candidates must have studied Mathematics

It is based on CMAT score. CDAC, SCIT are the colleges which provide MBA IT and both of them conduct their own exams. For SCIT, you need to give SNAP and CDAC has its own exam.

Yes, you can do MCA after BCA in two years as it is PG course.