Depending on from were you are, or you depart, the best way to get Oaxaca is by plane through Mexico City, I think that the fare from abroad to Mexico City would include the portion to Oaxaca, a guess. There is a lot of great places to stay for a very reazonable price. I don't think you need an escort, maybe a guide by the hour for some places. If you are interested in documentary you can take this workshop: http://www.pcnw.org/school/workshops.php#maryellenjuly, it's an incredible experience. You can also google it to find more photography workshops, there is a few through the year.