Hi John. I read your job description carefully and checked.
There is a detailed guide how to do that.
[login to view URL]
I think it can be done within a few hours.
I guess it is good to pick second case, File server configuration.
If you choose first one(to use one of your 3 members computer as main one), then that computer should be turned on always.
If you are 3 members, then you can buy cheap vps with windows server and use it as file server.
Hope to discuss more in chat.
Thanks.