Does backing up the single VMWare Fusion's virtual machine file to be suffecient to backup the entire virtual machine? Does backing up the single VMWare Fusion virtual machine file sufficient to backup the entire virtual machine? Meaning if I use that single file on other Mac or PC, will it run as it is?
On a Mac, when you copy the virtual machine file, it is actually a directory with all the files included that you will need to run it on another machine.

Shut down the VM before you copy it otherwise it can give issues on the other system. If you look at the folder you copied afterwards, you will see a bunch of files. The important ones are all grouped with VirtualMachineName.vm* and VirtualMachineName.plist and VirtualMachineName.nvram

You can remove all the other files.

The one with the .vmx extension is the config for the VM.