Very interesting stuff here. You do have this low GPA problem (and if it is 2.0 it is very low, I won't lie to you buddy), but still you have a profile that otherwise is extraordinarily strong. I mean your successful VC startup which led you to bigger and greater things in this world. As you probably know VC is one of the strongest industries you can come in from, so that will help you a lot.
Now as much as it is a shame for your GPA, you have done the best thing you possibly could by getting that 720, which proves that you are a smart guy. And I think you don't need to take the GMAT again (actually I think it'd be a waste of time). But you will need to carefully strategize your application, esp. what you are going to say about your GPA. Being involved in rugby + owning up to immaturity + showing that you are clever through your work and GMAT is the good way to go, but besides that your essay will have to have feeling as well.
Taking a few extra courses and getting a bunch of As can help a bit, too.
I do have good news for you though. From first glance at what you have written, I think you may actually be under-evaluating yourself. And the schools you listed as "stretch", you would probably actually be competitive at. And the other schools would be more "Safety net" schools, and I think you can choose one or two of those.
As for the MSc - only if you want it. Don't go for an MSc as a backup choice, if you don't need/want the knowledge. I think you can make it into a good MBA, and anyhow getting an MSc would not help you as much as other things (say getting another promotion).
I hope this helps you out!
And if you have any follow-up questions, you let me know!
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