If you move the PDF files to a new folder, the .pdx catalog file will break. Always keep your PDFs and their index file in the same relative directory.
If you are using Acrobat Pro for research or legal work, the is your best friend. Unlike a basic "Find" (Ctrl+F), an index creates a catalog of every word in a PDF or a collection of PDFs. Why Create an Index? index of acrobat pro
This looks solid. I will proceed.