A. There is no meaningful Fiery upgrade path for your machine. There were 2 generations of Fiery's for that model but even the latter has aged out of Command Workstation 6.6 support. It is still supported by Command Workstation 6.5 which should run on macOS 11. Fiery Command Workstation is not involved in scanning, so it's not relevant to this question.
B. You can connect the Xerox directly and use it without a Fiery. But that's probably not going to help if you're trying to use SMB as your transfer protocol because the model Xerox that you have only supports SMBv1. Additionally if you have a Fiery than the Xerox probably doesn't have an optional PostScript enablement you turn the Fiery on it should discover the Xerox and they'll both be directly connected to the network. The Fiery startup page will indicate that the device is configured in 'Network Switch' mode if that's still enabled.
C. Your best bet is probably to install 'Fiery Remote Scan' via the Fiery Software Manager application and use that to get scans to your clients. Remote scan is separate from Command Workstation and it's free. Using Remote Scan your scans go to a mailbox on the Fiery and then those mailboxes are mapped to a folder on the local workstation. When the user opens the folder it shows the files that reside in the mailbox on the Fiery as if they are on the local workstation. I use remote scan primarily at print for pay customers with little or no IT support as it allows me to easilly train operators to be self-sufficient when it comes to creating and managing new scan templates.
All of this aside I recommend that you consider upgrading your MFP to a Xerox PrimeLink. Staying current with Apple products often means staying current with other devices to ensure compatibility. It's not like Windows where we can, for the most part, just make older devices work nearly forever.
Good Luck!
