Hi
HullDown,
thank you very much for sharing your profile. I am sorry about your brother.
It is true that a 2.3 GPA is not that great. Though you could talk about extenuating circumstances in your application (the Optional Essay is a great place to do so).
However, even if there were no such circumstances, you can focus on how your brother's accident meant an inflection point in your life, and how this made you become the mature person and professional you are now.
Moreover, European schools don't put as much emphasis on GPA as US schools do, so most likely they will let that go if you're able to put together an outstanding application.
Your profile is quite unique for your target schools, since they don't get that many applicants with military background. Furthermore, I am sure your time as a military officer will be a great source of stories for your essays.
In terms of GMAT, if you get a 710 in the actual test that would be fine. But try to score higher (+720) if you can, especially for HEC Paris.
I hope this helps.
Good luck!
Alex