You can add quite a few different metadata fields in Lightroom. Next to metadata in the right panel in Library select any of the other views to show many more metadata fields. There are many different fields that could do what you want. Creator would probably be the logical field for this purpose.
You can't password protect anything in any file that others can read. Anybody can rewrite a file with different info in any field if you are able to read the original file. It is logically impossible to password protect something that you want readable to the world.
Thanks everyone that provided assistance.
Adding creator would indeed take care of my first question.
As far as the second question goes, it looks like maybe I have to look more at the watermark feature. What I was trying to do was put some unobtrusive identifier on a photo that I might put on the internet that would not be alterable and readily identifiable should ownership ever become an issue. Password protecting fields just seemed the most logical way to do that.
Thanks again! Very much appreciated!
I struggled with the same issue. It is important to have metadata included in your files that document your ownership. It is extremely easy to strip that, just as it is quite easy to crop or clone out an unobtrusive watermark. However if people strip the metadata from your image or clone out a watermark it quickly becomes willful infringement in which case copyright law allows for extra damages. so it is important to do both but realize people can and will still steal your images.