Exam

For Masters from Canada, you need to score 6.5 overall with not less than 6 in each module.
I don't know about the scholarship one.

You need minimum 50% in UG, but if you score high, then you can attend high quality company's placement and for IIM -A, B, C, you have to score over 98 to 100 percentile in CAT.

Yes, if you wish you can select any optional subject.

You can appear for JEE after taking admission in first year of engineering. However, you are advised to check policy of college with respect to withdrawal from study after first year. Colleges put heft penalty to discourage students from doing it and also to avoid losing out revenue of seat for

You can appear for exam like IIFT, I think in India no other college is as good as IIFT (Indian institute of foreign trade) for international business.

There are lots of colleges providing you MBA but according to MAT only few best colleges are there which accepts 95 above percentile.
It is better for you to check colleges by your percentile on Shiksha instead of asking others because no one will tell you the best college, but do MBA from Bangalore

List of Top 10 MCA Colleges in India 2016:-
1. Department of Computer Science University of Pune
2. School of Computer and Systems Sciences JNU New Delhi
3. School of Computer and Information Sciences University of Hyderabad
4.NIT Trichy
5. Birla Institute of Technology Jaipur
6. NIT Surathkal
7. MNNIT All

JEE exam 2017: No weightage to Class XII marks, news is published in Indian Express.