Copyright Questions

So I have been putting together a manuscript for publication on the Cane Creek Massacre (I'll probably use an on-demand publisher since I've not had luck grabbing the interest of a traditional one). So I am sorting through my collection of photos and trying to determine which ones I can use in the book. After some research I think I have a good set of guidelines, but I want to know if others have a better idea of what I can legally use.

• Prior to 1998 a copy right would last for 28 years but could be renewed for an additional 67 years, for a total /max of 75 years. After 1998 copyrights last for 95 years
• For all items published before 1923 copyright protection has expired. I can use them but only if I scan them myself directly from the pre-1923 publication. Digital images have a new copyright that restarts when it is created.
• The copyright for items published from 1923 through 1963 has also expired unless it was renewed. Scanning an image would create a new copyright, but usually only for the digital image. It is a safe bet that the copyright on commercial images have been renewed.
• Unpublished works are protected for the life of the creator plus 70 years.

There are more laws surrounding copyrights, but these are the ones that apply to what I am doing. So when I find an image I want to use I have to figure out a couple of things

• When was the photograph taken? and by whom? Most of the images I am interested in predate 1923.
• Where is the original today? who owns it? and can I scan it myself?  In most cases the legal owner of the photo would a descendant of the original photographer. In some cases it would the institution to which the photo was donated.
• Who scanned the original image? The "when was it scanned" is not an issue. Except in extremely rare cases, it would have been after 1990, and most definitely still under copyright. Of course, there doesn't have to be only one original. A post card showing the John H. Gibbs and William S. Berry was published in 1884. That card is certainly out of copyright. While the digital image in still copyrighted by the person or institution that scanned it, I also own an original of the post card and can scan it myself. Then I hold the copyright on my digital copy of that image.
• I have an image of Ruben Mathis, a vigilante who saved the life of Elder William H. Jones. It was taken in 1934 probably by James M. Kirkham. If the image was never published, then the copyright would still be in force. Kirham died in 1957, adding 70 years would mean the copyright expires in 2027. But if it was published, the copyright might have expired as early as 28 years after that. Even if the copyright has expired, the digital image is under the copyright of whomever scanned it (assuming they had permission). So if I want to use this image, I have to find who owns the copyright today. That means tracking down President Kirkham's descendants, or perhaps figuring our which institution he might have donated it to. Some of Kirkham's photos were published in the Church News, but not all of them.

As I go through my photos, I'll have to ask these questions about each of them. The question is, am I missing something?