1. When my PC came with Win7 pre-installed, the start menu showed 'Shutdown' as the default, only changing to 'Sleep' after I had used the sleep functionality for the first time. It was easer to find because it was only one level deep on the only visible control on the taskbar and therefore drew attention.
2. I did notice the power button on the Win8 log-on screen, but I was logged in when I wanted to shut down. I knew there had to be a power button somewhere without logging off, but I couldn't find it; it was not discoverable.
3. The iPad is a tablet that is designed to be left in sleep mode and not powered down -- I am using Win8 on a small laptop which is designed to be switched off when not in use. My main PC is a desktop which is definitely going to get shut down when not in use. If I were to buy a Win8 Tablet, I wouldn't worry about the power switch because I would expect a tablet device to sleep. Win8 seems to be a tablet designed OS which is being marketed as a desktop OS.