India

The cut-off for CSE in BITS-Goa lies between 317 to 330 marks in 2017. I don't know the exact iteration number, but probably it's 3rd or 4th.

Congratulations for your score.
Yes, definitely you should go for CAT, XAT and CMAT.
They provide admission opportunities in India's best B-School like IIM-A, B or C, XLRI, Jamnalal Bajaj and SIMSREE.

B.Sc (PCM) has less scope in terms of career and jobs as there is more demand of technical profile. Jobs are available but salary is very less and more hard work is there. The scope in India is average in this field but there is more scope abroad.

The exam takes place somewhere in the month of December.

Yes, Kannada is a mandatory subject in KPSC.

International MBA or PGDM is very expensive. Return on Investment is better if you do PGDM from Tier I Business Management Schools. Therefore, it is recommended that you op for PGDM from Tier I B-Schools in India.

Yes, you can definitely get a seat in KLU with a rank under 10,000.

SRM University is a better option as it has a better brand value.