A couple of thoughts. I used Paintshop Pro for many years, and after joining Lenspiration am trying out Lightroom Classic. I didn’t find any obvious way to modify the metadata (like copyright) on multiple pictures in PSP. The most common ways for folks to steal your photos from the web (any site) involves right-click / save as… and screen shot. Disabling right click solves one of those, decreased resolution at least partly solves the other. It is a moral choice – if someone wants to steal your photo, they can probably figure out how to do so. Such a person is not likely to be deterred by a copyright or permission notice.
If you take the photo, and are not being paid to do so, you own the copyright without doing anything else. Legally, if there is a dispute, you might need to prove when you first had the copyright (if someone else claims they had prior claim). I don’t think you need to put the full agreement on the website. James, I believe, has a simple statement to contact the photographer for terms to use the photo.
Putting your work (photos) into public domain is just that – putting an unlimited stack of copies in an airport for anyone to take and use for any purpose. So, if someone using your photos for evil purposes is an issue for you, or you need to generate revenue from them, take what precautions you can (copyright, permissions).
