Hi there!
Thanks for your inquiry. Since you have specific questions, I'll address them directly. The way you stand out of from an overrepresented pool is to excel in what you do. Leadership experience and capabilities are essential. So when you're getting involved in something, don't just participate, become engaged, emerge as a leader, and make a direct impact. Also, when thinking about getting involved in extracurricular activities, don't just do it for the sake of doing it. Think about why you want to do it (hopefully it's more than just to pad your resume). Find something you really care about and commit to it.
Your GPA is very important, especially for top programs. As an engineer, you might be compared to other engineers, so simply having an engineering degree doesn't set you apart. If your GPA is low and you are only in your 2nd year, the good news is that you have time to do something about it!
You really won't get what you want out of an MBA straight out of undergrad. The median age for most programs hovers around 27-29. While some schools like HBS, Yale, and GSB are looking for younger candidates, you will still need some work experience. A deferred program like the ones you listed are good options if you're interested in going early. And no, being rejected once won't hurt your chances later assuming you've made substantial progress in your career and other facets to improve your application.
Hope this helps! Feel free to check out
our free resources to learn more about the various program options and how to pick the ones that are best for you! Best of luck!