Your age in and of itself isn't really how the adcom will benchmark you - they will be looking at your grad year (i.e. how do you compare to others in your grad year +/- 1 year).
In any case, I think based on your overall profile, you'd be a stretch for the top 8 schools at this point -- *however*, with 1-2 extra years of experience and some more meaningful extracurriculars, you should have a stronger chance. In other words, to be competitive you need more than just "I'm more accomplished than others my age" because while you're young now, you're not *that* much younger than others (1-2 years) which over the longer term isn't going to make much difference anyhow. As for the kinds of things you should or want to be doing outside of work, that is entirely up to you so long as it's an organized group activity - arts, athletics, nonprofit, social/political orgs, etc.
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