hi there, keep in mind that there's no certain path, WE, or major that will get you into b-schools. Top business schools accept people from all over the spectrum. It really matters little what your title stands for, but the emphasis will be placed more on your qualities and leadership ability. Just because you work in a hospital doesn't mean your work experience is not better than that of MC or IB. It simply means that you can bring additional diversity into b-schools and contribute in the class discussions. So instead of thinking about "increasing chance to get into a good b-school", do what you love and do what you want to do, then worry about b-school admission later on in life. If you want to volunteer, volunteer at a place where you know you'll enjoy the work. One thing for sure though is to gain leadership ability. Think about where you can showcase your leadership skill at work or in the community. What do you care about in life? Voice your opinion and advocate for something of your liking. If you believe that a local park should not be converted to a shopping mall, do something about it and take actions. These are the type of leaderships that will get you a turn-of-heads. In terms of classes, take additional business classes at local colleges is a great idea, but only do it if you're interested in it. Having said that, b-schools do kind-of expect you to understand the basics of calculus, statistics, and macro/micro-economics. So if you haven't taken these courses, it might be good for you to take these courses. In terms of how long you should stay at your current position is to your discretion. Again, there's no magic formula that says 5-year-of-WE + x.xx GPA + xxx GMAT = Harvard (or whatever b-school to that matter). You should think about when you can put in the strongest application. I'm not sure how much I've helped in my post, but I hope it can get you thinking about some of the things.
Get the best GMAT Prep Resources with GMAT Club Premium Membership