I'm not sure how to evaluate your SSC, Inter or B.tech, but your GRE is pretty low. If you prepare for it and retake you should be able to get a higher grade - I'm guessing English isn't your first language, so the verbal part might be harder for you, but you really need to get a higher GRE score to have a decent shot - at least 1100 to 1200.
A reminder email is ok. I had to send a couple reminder emails when I met with a POI earlier this month. They really are busy and you just have to follow up politely.
Some of my replies were like that, but its good that they have space for new students. Did you ask about current research? And by this I mean stuff that's not readily available on their websites.
Hi achapiro, GRE scores aren't considered very much by top schools, in fact I think I read that MIT doesn't even require the general GRE. That said, bad GRE scores can be problematic. You, however, got some good scores so I'd say that your chances are pretty much the same as they were before, which given the consensus so far, is that you definitely have a shot, especially if you get good letters of recommendation.
Mention it in passing - so in a sentence about the conference and your experience there, just slip in that you got awards like it's no big deal. The writer of this SOP did a pretty good job with that: http://ls.berkeley.edu/soc/diversity/apply/samplestatement-1.html
That sounds like a good plan. I think the fact that you are doing experiments on your own will help you as it shows your initiative - admissions committees love that. Definitely apply to a couple top 20 programs in addition to those in the 50-100 range you apply to. You never know if you'll get in unless you try, so give it your best shot!
I think you should consider who knows your work best and also whose work is best known in the field you are pursuing. Having too many people wanting to write letters for you is not a bad problem to have:) Since most places require 3 letters, maybe you can identify who would write your strongest letter and have that person write to all your applying schools and then alternate the other profs (who would write strong letters) to the other schools your'e applying to?
I got some of those last year as well. My advice is to independently find schools that are best for you - consider the schools that send you mail if you hadn't before, but don't be swayed by them just because they sent you mail. Don't look at it as if they're pursuing you in particular - they're not. They're trying to get applications from as many qualified people as possible. Last year I got emails from a top 10 Ivy league school (based on my GRE scores I think) - needless to say, I didn't get in when I applied.
I have a question as someone that's been out of academia for a few years and looking to go to grad school. What would I put on my card for my affiliation - would I put my job title and current work place, or would I put something like 'independent researcher'?