Three or four sleeves will hold enough for most use. We generally provide flat carry bags, map tube cases or some form of tubular container like a quiver for carrying to protect pictures. In some places it has proved helpful to bind the pictures along the topedge to keep them in a certain order for use, and to minimize loss of pictures from the set. This prevents multiple users unless used at different times. Language Recordings International flipcharts are already bound.
Pictures are very good for illustrating certain foreign or unknown concepts.
Crucifixion is one illustration. Pictures suggest relationships in the stories as those Jesus and his disciples or those coming to Jesus for healing. Even facial expressions convey an intensity of emotion to viewers. Without a visual illustration people create their own mental image which may or may not be correct. On the negative side, what is displayed in the picture may be distracting as it offends some cultural convention, or is simply puzzling to the viewer who has a limited visual literacy.