Tech Nerd?!! Did somebody call? I am just that (A+, N+, Windows 2000 Professional, and Windows 2000 Advanced Server certs with a college degree in Computer Science). Does that qualify me?
A. Electricity usage should be no concern, it is minimal. Your alarm clock uses as much.
B. Turning electrical objects on and off causes more "wear and tear" than anything. For instance, a lightbulb most often goes out when it is switched on, as the current surges to it and overpowers it. Also, your hard drive receives it's biggest "workout" when it is starting up.
C. Here is the key issue. It's called SECURITY. If your dad is concerned about "anyone" accessing your computer, why did he get a wireless router? Wireless had VERY MINIMAL security. It uses airwaves, and you have no control over where it goes. All over the country there are cases where someone is discovered accessing a wireless network illegally. Read the post titled ""Surprised to find network at home: what to do?". One guy in my Advanced Server class told us how he went to a residential area in town, powered on his laptop, and had it search for a network. It gave him eight available networks. So, he could have used any of those networks to, say, download some kiddie porn. All using someone else's IP address. Sound safe? Even with a firewall, encrypting your signal, or anything else, there has yet to be any wireless network that is as secure as a wired network with a simple hardware firewall. Why do you think companies aren't purchasing wireless network the way "home users" are? Do you think home users are more knowledgeable? Or maybe home users are more concerned about protecting their data than a business is? There is a reason they aren't converting from wired to wireless. At this point, it isn't safe. Period.