IIM

Start preparing for the competitive exams like CAT and GMAT form the first year itself all the best brother or you can get some work ex after your graduation and later on can go for MBA.

To get into IIMs, you need to get around 99% in CAT and to get into reputed B-schools you need more than 80%. Your competitors matter and how the exam is going to be evaluated also matters. Every year evaluation criteria changes. Keep a close eye on the exam patterns and be in touch regularly with your coaching institute, they will help you get better.

Hi,
As of now, IIMS provide only PGDM degrees. It does not provide integrated MBA.

As far as Great Lakes is concerned, you have slightly dim chances.
All the best.

There is no specific eligibility criteria for class 10th and 12th percentage, there are just ratings associated to these scores. So, it is recommended that you aim for a high percentile to make it to a good IIM so that your ranking based on a weighted average score is good.
I cannot pinpoint to a specific score because it is all relative, but you should aim for a percentile >99.

The current fee amount is Rs. 21 lakhs for two years, which includes tuition and accommodation (excluding food expenses).

Yes, but you should be very clear about your thought process during the interview.