MD & DO 2nd Bachelors

Hello,

I already posted about the possibility of MD/DO with my less than fabulous undergrad GPA:

2.22 sGPA, 2.76 cGPA

so far I have re-done most of my pre-med classes and have a post bac GPA of 4.0

Questions:

1) Even with post bac, my GPA is still 3.14. Will my stellar 4.0 GPA make up for my lackluster undergrad? Or should I pursue a BS in Microbiology?

2) I have seen varying answers on forums -they will average my science grades correct? They wont take the best ones...

Additional info for evaluation: 6+ years of volunteering abroad (peace corps) and domestic- w/kids/literacy/clinical/hospital, 250+ hours shadowing , quad-lingual ( English, Spanish, French, Pulaar), and hoping to add research into the mix over the next year

Thanks