I assume you'll take the GMAT soon? Or at least work on your essays in conjunction with your GMAT prep for R2 deadlines?
Generally you should have time to apply to 2-3 schools for R2, yes, depending on how much time you have on a weekly basis, when your GMAT is, how much prep you are doing for that, etc. Keep in mind that R3 can be pretty challenging, because so many seats are usually already taken in a given class. So I would prioritize and apply to the schools you are most interested in sooner if possible. It sounds like Kellogg would be a great match with your marketing passion.
It sounds like you have a strong profile if you do well on the GMAT and put together compelling essays. The combination of your financial background, some start-up experience, athletic involvement, and international experiences should provide you with some interesting stories to draw from in your essays and in the classroom.
Keep us posted on how things go with the GMAT and other questions, and good luck on your progress!
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