1) No, that LAPTOP only has Windows 10. No other OS. The DESKTOP has Windows 7.You only had to think about it because you were trying to reboot the computer to get into a different OS, which is something 99% of users don't do.
An update notification doesn't prevent you from leaving for the day unless you are a sysadmin. Any regular person just walks out of the office and leaves for the night if they go to shut it down and it says it's updating. The updates don't require user interaction.
ChromeOS only displays the verbose text to a user that it's updating if it's in developer mode. Otherwise it turns itself on in the middle of the night, updates, and then turns itself back off, which is what your Windows 10 computer would do too if you weren't dual-booting it.
2) Apparently you do not work with professionals who need to take their laptop home with them every day and work from home. Some put their laptops to sleep, some shut down.
3) I am not dual booting Windows 10 on my laptop. I am not dual booting Windows 10 in a traditional sense on my desktop. I have Windows 10 on one disk on my desktop. I have Windows 7 on another disk on my desktop. When I installed Windows 10 on my desktop, the Windows 7 hard drive was completely removed. When I am running Windows 10, the Windows 7 hard drive is disconnected. When I am running Windows 7, the Windows 10 hard drive is completely disconnected. Both drives single boot to their respective OSs.