Hi,
Mohsenafra. Wow, congratulations on your success. Immigrating alone at 15 sounds incredibly challenging, and I admire your resilience and ambition.
To answer your questions
1) You should be OK here, but while there are no hard and fast age limits, once you get into your 30s, you start aging out of the 2 year MBA programs a bit--both on their end and yours - you start to be a little less of a fit for summer internships and you also start to feel less of a "peer" with your classmates. It's not impossible, but your chances become a bit more unpredictable in the process.
2) If the list you've provided is your target school list, then yes, I encourage you to retake your test. While it's POSSIBLE to get into schools with scores below their average, a 680 puts you 50-60 points below, which is a big gap, and again provides a point of hesitation, especially since your GPA is low.
3) All these schools are looking for impact and leadership both on the professional and personal front. I like hearing about how you've been promoted already 5x in 3 years and have made many improvements to the company. Keep doing what you're doing there! But if you're outgrowing your place of employment (and it sounds like you might be), moving to a target consulting company might be helpful...try to keep making that impact once you get there in the bigger pond if you can. And continue to step up in these extracurricular efforts - some of these sound quite promising!
When the time comes, make sure to tell your personal story...differentiating yourself and showing your character will be important and especially use the optional essay to give context to your GPA. Good luck!!
Warmly,
Julie-Anne Heafey