How to safely migrate from Mavericks to High Sierra?

Question

macOS

Greetings
Everything suits me in Mavericks, but the other day Chrome told me that it would no longer be updated on this OS, Opera went down and other software updated by developers can no longer be installed. I don’t want to go over, but the situation is such that, apparently, this time has come and there are several questions about this:

1. A bunch of software is installed, will it be necessary to make a list of it and after installing Sierra, reinstall everything again or reinstall only what does not work under the new OS?
   
2. Should I make backups of important data on the disk and then "upload" them, or will everything where it was there and remain?
   
3. Is it better to completely reinstall with erasing everything that is, so that there are no errors and everything works as it should, or is it better to do a regular update and everything will be as it should be?
   
4. I'll understand later, but maybe one of you had the experience of switching from Mavericks to Sierra - is it more voracious than Mavericks or not?
   
5. How long will it take to update with a bunch of software - long or no difference?
   

Answer 1

Everything is updated without problems. I did not notice a difference in the brakes after the update, unlike a clean installation. I had to update some software, but this is the norm)