Well the first thing I would say to you before I even evaluate your profile, is that your profile and your applications is in YOUR control. The way you have presented yourself here, is bit "I'm a regular guy with an awesome GMAT"... which is not bad... but why be a regular guy? Meaning it is up to YOU to define how you will present your story and make yourself passionate exciting and unique to the AdCom.
Now, on to your specific question:
1. There are no specific colleges which look only at GMAT. All schools will look at your entire package.
2. The way you present it, not much...
Buuut, as I have discovered many times during my many years of helping folks out, you may be underestimating yourself.. you may have more in your profile than you think.
3. With good essays, Top 20 may be reachable, even if Top 5 will be a challenge. I would still recommend one or two safety schools outside the top 20 (but not too far outside) jus tin case.
4. I would keep an open mind here. Basically school choice should be based on a mix of fit, how it fits with your goals, personal preference, ranking and chances. I'd say that any of the top 20-30 schools could work for you. If you are staying in IT, there are schools which are known for their strengths in that industry.
5. Yes, unfortunately. This is something you will need to address in your application.
6. I would go for schools that are well-ranked with strengths in your industry and good employment records... schools like MCCombs, Georgia Tech pop into mind first, but there are certainly more
I hope this helps you get started, and if you have anything else, don't hesitate!
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