yes cut a fragment of the photo skin. choose projection mode and paste it on the model, you can scale it and then you have to choose for drop. thats it.

if you going to use DP3D than i advise you to export neck + head. and begin texturing on the side of the neck and head textures and then work your way to the front:)

Of course the front photos dont always have the same color or darkness of the side photos. no matter how good your lightning in the photos are, its inevitable to get some difference in color. so if you are in projection mode you can choose the option to go to photoshop ( i recommend CS2, the rest has some problems with DP3D) and then you can color edit the the photo fragment. and if you are done go to DP3D and choose import from photoshop. after that go out of projection mode and tadaa you have the same color as the rest of the face. its not hard but it takes forever though.