Hi there,
Thanks for posting and glad you've enjoyed the forum!
CONGRATS on the 750 GMAT, that is a great accomplishment, and no I wouldn't suggest a re-take.
So your grades are below the averages at top schools, but not SO much that I'd be super-worried about it, especially with the great (and recent) GMAT. Your experience as a lawyer could bring a unique perspective into the classroom, but just make sure you do make that clear and compelling case for the WHY, as occasionally some law applicants struggle to do (you don't want it to sound like you are trying for the MBA just for lack of knowing what else to do next, for example). Yes there are a number of lawyers who apply, so not saying it's not competitive among that group, but it's generally still a smaller applicant group than say investment bankers, consultants or even engineers these days.
Sounds like the lack of much community involvement would be another small weakness, as you acknowledge. You'll want to do some brainstorming about what you DO have to offer and what you feel you can contribute to the class-- your unique perspective and experiences; leadership examples; teamwork; communication skills; impact you've made; accomplishments; passions, etc.
Age could be a minor factor but also understandable given your training etc and 4 years of FT experience is very common.
I think Booth, Columbia, Tuck & Yale are good options to apply to. Keep in mind that many apply to 3-6 schools; each app is quite time consuming so be careful your school list doesn't get TOO long that you end up sacrificing quality of your apps for quantity! Also your recommenders will have to do that # of recs as well.
As for goals-- you are right in that whatever you describe, should come across as genuine, something you are passionate about and realistic. It's true that the more exposure you've had to that area and ways you can say influenced your choice of that area, the better.... not saying you can't do so with your current options, just something to think about.
Hope that helps, let us know if you have further q's, and if interested we do offer a free 30 min consultation option at any point, at
https://www.mbamission.com/consult/. Good luck!