Hey Phoenix - wow that quant score is impressive! Unfortunately though, the overall 660 is much lower than what an Indian tech guy needs to get into a great program. The bad news is that there's just a lot of candidates "like you" applying - yes, even with the "started my own venture" and the "CSR initiatives" and the other angles that are adding some nice color to your profile. The GMAT is not the most important part of a profile, but a lower score like this can really be an obstacle.
Your college internship does 'count' in terms of adding to your profile; many Indian candidates don't have that, so it's certainly additive. It's not full-time work experience though, if you're asking about how to calculate that number for your apps (many schools ask for candidates to indicate how many months of experience they've got pre-matriculation; you won't include the internships there).
The GPA is fine, you actually don't need to worry about converting it to the 4.0 system, most schools nowadays want you to simply report it on the scale your school provided. The 7.6 is again not overly distinctive; it's not bad (not a weakness) it's just not going to 'wow' anybody.
The very good news in your question though is that you're asking about a wide range of schools, which means you're realistic and flexible. If you absolutely do not want to take the GMAT again, then yes you could have a shot at schools like Kelley or Mays with your current score. Without knowing a lot more about you / your profile then we can't say one way or another if you would have a real chance at Kellogg, UVA, etc. - but you might, especially if you bump up that verbal side of your GMAT.
It sounds like you tested just once. You're early enough in the admissions season that we strongly recommend you try the test again. There's literally no downside to it and a higher score could have a very significant ROI for you in terms of options it opens up.
Hope this helps - let us know if you have any follow-ups and we'll be happy to address them.
EssaySnark Essays Reviewed on GMAT Club FOR FREE!