We like more mature students, for one.
I guess I would be considered non-traditional. How does having a doctorate and professional license factor into admission decisions?
Well, you're expected to do well. A 2.9-3.0 is not doing well, and would imply you have trouble in med school.
Would the rigor of the coursework be taken into account when looking at my GPA if explained to admissions?
Yes. At least get the GPA >3.0 to be more palatable to DO schools. For MD schools, you'll need to ace an SMP/post-bac and have a good >33 MCAT.
Is a post-bacc or masters program absolutely necessary to make me a viable candidate?
For MD schools, even a 45 won't. You're expected to have a great GPA and a great MCAT score. DO schools would be more forgiving, but you'll still need something in the high 20s.
What kind of MCAT score would I need to overshadow my GPA?
The standard stuff that pre-meds do. In your case, you'll also need to demonstrate that you wont' bail on Medicien like you did with Pharmacy.
If I were to complete a post-bacc/masters, what kind of ECs/experiences should I seek to beef up my CV?
Totally up to you. Just take it when you're fully ready. Scores tend to stay valid for 3-4 years.
Also, if I do chose to take the MCAT, should I do it ASAP before the 2015 version is introduced? How long are scores valid?