Let's talk for a moment about your antivirus concern. So far all file sharing is simple in that if a virus (trojan, malware, and so on) is on a machine that connects to said share and if the machine+user has the rights, the content can be tampered, deleted or infected.
There is nothing amiss here. It's how it works today and why you read so much about having backup copies.
About the printer, we could connect such but I find such a thing to be onerous to setup and maintain. This is why I went with a wifi capable printer. Done and a lot less hassle.
Finally there is that issue or goal of one device that does all this and does nothing particularly well. The Apple Airport comes close. Did you look at that?