It's legit, Anon. Offers a number of programs for business, medical, and other fields to provide trips to locations like your grandkid is going on. Make sure your grandkid registers with campus study abroad/international office to ensure campus knows he/she is abroad for risk mgmt.
Yes. Usually these trips are also coupled with recognized student/university organizations on campuses so if things change in location of trip, Global Brigades will cancel. They don't do locations that are unstable like Venezuela right now, but they do go into areas of need like Honduras. Kudos to your grandson for serving those in need especially being pre-med.