If overseas stuff is what you want, when you're looking for places see if they have any established regular overseas missions trips or relationships with medical institutions overseas. Check to see if there are faculty with global health interests on staff and also see if they have any established student interest groups regarding global health and what kind of things they do.
As far as MPH, from what I understand from my friends with them it will better prepare you to work with policy, which some like and some don't. If you want to just do global clinical hands-on-patients work, an MD is fine without the MPH. If you want to work with the Cambodian government to develop a program that will get HIV+ moms perinatal antivirals, get the MPH.