Best way to backup Hacintosh

1. What is the best way to make possible double boot Windows/MacOSX? I want some kind of boot menu before start.
2. What is a proper way to backup already installed Mojave and to restore in case of some failure? Is TimeMachine is the best option to do it or Acronis will be better?
3. What about OS updates? If my OS works nice now, can it break after some minor update? How to prevent it? Still can not feel that Macintosh can be a primary system with such risks

BTW, I have problems with Dell Wireless 1601 802.11 a/g/n Adapter and nothing helped. Could someone help me to fix it on Mojave? I found this thread, but still have no idea how to install it

Thanks in advance