I wanted to add a couple other points to the list. I´m not sure how to encapsulate it this in a bullet point, but the dynamic of “sending church”/”host church” needs to be broken down. The hosting churches need to also be sending, and the sending churches need to also be receiving. When we as North Americans assume that a calling to short term mission (or any kind of mission) is only something for us, we are involving ourselves in dangerous ethnocentrism.
I am working with volunteers here in Nicaragua, and we have committed to giving equal opportunity in ministry and service to North Americans and Latin Americans (ie, if we received a North American group, they either partner with Nicaraguans to go to another location and/or help to sponsor a group of Nicaraguans serving somewhere else).