Motherboard Transplant

I bought a new PC case that will be getting here in a couple of days, and I've been reading up on how to install a motherboard in a case. This is the first time I'll be doing this, so I'm a little nervous. I have a couple of questions that'll hopefully be answered here. First, does it matter in what order I unplug and plug the power supply and devices from the mobo? Should I unplug the ATX connection first and then the hard drives and all that stuff, or does the order really not matter as long as it's done within reason and logic? Same goes for plugging everything back. How should I hold the motherboard? I also read about metalized screw holes on the motherboard that don't require washers. My motherboard has little metallic dots around the holes. Does this mean they are metalized? Any other suggestions or precautions you guys have are welcomed.

Thanks, 3! However, in my particular case, the motherboard tray is not removable. How do I got about installing the standoffs?