There is a catalog of photos located on an external drive. Will Lightroom recognize these photos on a copy of this disc? What is the best way to make this copy? Simple copying by windows explorer? Or is it better to make a copy of the volume?
You are asking a lot of questions, so rather than answer each one individually, let me explain the process.
If you have photos, and you make copies of them on another disk, Lightroom Classic does not know about this other disk and does not use it. If you want Lightroom Classic to use the photos on this other disk, you have to point the software to this other disk. The process is explained here (in particular see Figure 4): https://www.computer-darkroom.com/lr2_find_folder/find-folder.htm