Not to get a battle started, but almost anything that can be done on a peer-to-peer can be done more easily on a server/client domain setup. I am not sure why you would be concerned about availability to your users.
The faxes should be routed to your server in a shared folder. I am guessing that all of your users can access Amazing Charts, billing software and any other files you wish to give them access to.
One of the advantages of a server domain is that each user must login with a user name and password, which is then authenticated against the server. Once logged in, the server recognizes that user and the user can access any data on the server which he or she has permissions to. So, if the fax folder is shared out to all domain users, then they will all have access to the faxes. If you only want certain users to have access you only give permissions to those users.
So, in short, yes it is simple to use an HP MFP on a domain, and any user can access the faxes.
As a caveat again, when you look at the specs online, be sure it specifically states that it is capable of Fax to PC and PC to Fax.
