Hi there! Glad you found my initial feedback useful. I just realized I mis-read your first post and thought you were planning to apply in 2016, not matriculate then. Got that now!
Thanks for your GMAT breakdown - AWA/IR are good, Quant is good too but a few extra points there could help you, Verbal is just below what we recommend so try to get that up to at least a 35.
So first of all, if Columbia is your dream then you should consider applying there early decision. They have already released their essay questions in fact! And since they use rolling admissions there is a benefit to applying early within the round too. So I'd say focus right now on getting your GMAT up and then if you can get your score closer to 710/720, get that Columbia app in as soon as you can. I do think given all your other strengths that it is worth applying there and applying early will demonstrate your interest and could give you a slight edge.
Here's my take on ECAs - they are not such a big deal that you can't get in if you don't have much, but if someone doesn't ANY, then it can be a concern. I think you've got enough to demonstrate some involvement. Also, I think there's a bit of a misconception that it needs to be formal volunteering work -- the work you've done helping students can definitely "count" -- as will other hobbies / passions (like your dance school) that show you are someone who engages in the world around them. One of my colleagues calls it having an "internal motor" - or having something that really drives you. So basically I wouldn't worry about trying to add on any ECAs at this point, you have enough to do with your GMAT and applications. Rather see if you can shape your past experiences and what really motivates you to tell an interesting story about who you are and what you'll contribute to the class. I think you can do this!
By the way, the Teach for India thing will not make a huge difference since it's short - but you could still list it on your application. I'm just not sure I would feature it on your resume or in your essays.
Keep us posted if we can help!
True. That is what I was hoping for - ECAs are not everything and they can only give edge to a person's character, not define all of it. I'll try to focus on all other aspects of the application and try to bring out the best of me.
Thanks a lot for your feedback! I really appreciate it. I might need some help when the applications begin and will be contacting you again then.