Just to clarify what turning on "File Sharing" really does:
- If you are on a computer and you want to share the files and folders on that computer with other computers on the network, then you would turn on File Sharing on the computer you're currently on.
- If you are on a computer and you want to connect to a share on a computer located on the network and access the other computer's files and folders, you do not need to turn on File Sharing on the computer you're currently on.
So yes, if you want the Mac Pro's files and folders to be accessible from other computers, turn on File Sharing on the Mac Pro. The other computers that will be accessing the files on the Mac Pro do not need File Sharing turned on.