GRE

Hi,
Refer to the official guides like The Official Guide to the GRE by ETS, Manhattan Prep and Kaplan GRE Prep. For IELTS you can refer to Official IELTS Practice Materials by British Council.
Cambridge ESOL, IDP: IELTS Australia, The Official Cambridge Guide to IELTS by Cambridge University Press and also check out preparation books by Kaplan.

Hi Anukul,
Different programs in Harvard have slightly different fee structures. Also, cost of attendance for international students is higher. Typically, it's around $45000 to $60000 a year. You have to check the program-specific websites for exact structure.

Hi,
You may. Applying to top ones will be challenging. Since your academics are moderate you have to prepare a very strong SOP and demonstrate your extracurriculars as well. LORs from your professors must be unique too.

Hi Anand,
Yes in US, GRE scores are accepted instead of GMAT. Always check university's website before applying. In India, a wide range of B-Schools like ISB, etc. accepts it.

Hi Uday,
Ideally, you can if you have met the other requirements like sufficient academic grades, good IELTS scores, etc. As far as the gap is concerned this will also depend on the nature of the gap, how valid and genuine it is. If it was work experience, it won't be considered as a gap. Now, you need to check with the universities for the specific requirements, GRE is not mandatory for all universities in Canada, so accordingly check on university websites and email them.

Canada sounds like a good option. However, you must explore some opportunities in the US as well. Have you already shortlisted some colleges for your Master's degree?