Thank you, Alex!
Only Hard. No worries about not compressible files. Pack will detect them and skip them automatically. Try it, and you will see that it processes 1GB of MP3, much faster than 1GB of TXT. I should note that it does not work based on file extension, so any file that it tries and sees cannot be compressed; it will be processed faster.
And for compressable files, like the previous point you showed about compressing to tar, it will still be faster to press them to store them.
--include lets you choose a file or folder inside the .pack file to unpack. So for example if you have a pack of Lazarus project, you can unpack only a pas file instead of all the project.
Yes, it throws an error if it reaches the end of the disk or file system limit. You will not get an incomplete file.