the most powerful image in this photo is this one because it shows that it is hard to be in the army and people do get hurt.

Set #1 At home in Denver - 1-7
Set #2 At Basic Training - 8-46
Set #3 In Iraq - 51-70
Set #4 Back in Denver - 71-82

the set of images where he was in Iraq was the most powerful because  it showed him feeling homesick and actually in the war and being part of  the war.

the images tell a story together by showing different events and changes in his life in chronological order.
present tense
the captions enhance the photo by giving a little more information about what is going on in the photo. this gives the viewer a deeper understanding of the photograph or a different view of the photo.