I think I understand.
The only safe way to reboot is using the Start Menu.
If you have a lot of windows open it will be better to close them each in the normal way.
Electricity, I can help, as I was an electrician before I retired.
Most laptop computers use small amounts of power. The actual amount is printed on the power supply, the small box which goes between your computer and the mains power.
Desktop computers change depending upon what you have in them. If you have a powerful graphics for example that will use more power.
The way to compare how much each item is using is to look at your light bulb. Most Laptop computers use about the same amount of electricity as a light bulb. Most Desktop computers use about 2 times or 3 times as much. A very powerful desktop might use about 4 times as much.
If you need to leave your computer unused for any long time, but do not want to turn it off each time, you can set it to sleep. That uses minimal power.
Does that help you?