To outline, I believe you have three possible options:

1. Poser The software includes four figures that can be modified (child and adult male and female figures). You can alter body shape, size etc. It takes some practice, but matching the basic body shape of an actual person is not very difficult. The program also includes a face room where you can theoretically import images of an actual person and then have facial features matched to one of the Poser figures. Theoretically because most Poser users deem this technique impossible. I would have to agree based on what Ive seen of the attempts. Facial features can also be adjusted through morphing and magnets. I have had success achieving good likenesses with this technique, but Ive been doing this for a while and prior to that had formal training in portraiture so I know how to get what Im looking for. You would also most likely need to separately purchase skin textures and hair props that match your subjects. Be aware that this isnt a program you will have a working knowledge of overnight or even after a week or two. The manual that comes with Poser is more confusing then helpful. I can usually pick up the gist of software very quickly, but with Poser almost all the knowledge I have of the program comes from hanging around these forums (and searching the net) month after month. You can easily export jpg images out of Poser into a presentation package like PowerPoint.

2. DAZ Studio Basically, very similar to Poser (but no face room). Free, but it doesnt come with figures. However, DAZ does offer a good selection of free basic figures. You would need to purchase morph and texture packages to make them usable for your purposes so the overall cost is probably around the same as Poser. I believe the learning curve would be the same as Poser, and again you can export images to a presentation program.

3. FaceGen - This is a very expensive program and results Ive seen are no better then what Ive seen done with Poser. Unless you want to continue doing this after this one project it really isnt a viable alternative.

So, bottom line Poser or DAZ Studio will probably work for your project. But any way you decide its going to take an investment of a considerable amount of time to learn how to do this properly for you purposes. I agree that you should probably download the Poser demo or a copy of DAZ Studio to see what these programs really are. You might also want to consider soliciting volunteers or paid workers from this community to help you put this together. Good luck.