Ritika,
Good to know that you are doing a proper research before getting full steam into CFA preparation.
Here are answers to your queries:
1. There is no exact number specified who clear the exam from india, but a sizeable number of condidates appear from india and a good number of people have cleared CFA.
2. Generally speaking Level 2 is considered to be the toughest of the three CFA levels and it happens once in a year (June) only. CFA level 1 is conducted twice in June and December.
CFA institute from last 2 years have started to conduct these exams in India. In june 2010, Delhi became a center too otherwise people had to travel to mumbai or foreign destinations to take the exam.
3. A lot of entusiasts who take CFA are either MBA students, working professionals or Graduates. I would suggest you to appear of CFA during your study time only as taking out time while working can become challenging. Frankly speaking the level is not very tough, but it makes sense to go for CFA coaching as you do not have the requisite background.
I have some friends who have cleared CFA examinations and would help you get in touch with them.
Regarding coaching institutes, there is a well known coaching institute in Mumbai by name Procore, it has also started its operations in Delhi some time back. You can go through this website for more details:
www.procore.in/