Hello! Sorry to make you wait.
1) I'd say that your chances are decent at Duke and UCLA. Michigan and Haas will be a little harder for you. You have a shot at Stanford, but you will really need to stand out with some kind of "wow" in your application, which didn't immediately jump out at me in your post.
2) Yes, this is on the lower side of work experience. It won't keep you out necessarily, but remember that you really need to have a great answer to "Why an MBA NOW?" and must be able to really demonstrate the maturity dimension in your application. (We discuss the "maturity dimension" in our
MBA admissions book.)
3) In general, we discourage applicants from focusing on the GMAT too much. But, since you have time, then you should consider retaking it and trying to score closer to 700 (more above).
4) Other schools like Tepper, Indiana, USC, and NYU (note that these aren't necessarily easy to get info, either) could be worth checking out. Also consider Vanderbilt or UT Austin.
5) I'd say that your low level of work experience is a weakness, as well as the risk that you'll have a hard time distinguishing yourself vs. other IT applicants. Definitely emphasize the things about you that make you an atypical IT professional!
Scott
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Co-Author, Your MBA Game Plan