1. I have a directory called /soft where I have several softwares that I have installed manually. If I make the upgrade on the operating system is there a way to mantain that directory, or ubuntu will just delete it all?

   
   
   
   
   
   • I have no idea. However, I like to believe that it will not delete it. The upgrade process upgrades packages and libs and all that, but not delete directories. I think they're clever enough to know that people create directories, even in the root directory. Also, don't forget that when upgrading through the Update Manager GUI, Ubuntu gives you a list of the packages and libs that will be upgraded, removed, and no longer needed, at which point you can choose to cancel the upgrade. I also found this: How does the Ubuntu upgrade process work? Look at the second, long answer. I haven't read it all, but it could contain some insight.
   
   



2. And what about documents such as the /home/{myuser}/Documents, what will happen to them?

   
   
   
   
   
   • Everything in your /home folder should stay as it is. I upgraded from 12.10 to 13.04 a few days ago, and everything in the /home folder was intact.
   
   



3. Will the installed softwares remain intact?

   
   
   
   
   
   • Well, it's yes and no, but more yes. The software will remain intact, but they might be broken and not work properly. For example, after my recent upgrade, VMware Workstation was not working. I had to dig through the answers and the Ubuntu forums to find out what exactly needed to be done, and I eventually got it to work. On the other hand though, other softwares work perfectly fine.
   
   



4. Is it advisable to upgrade the OS via terminal or is it better to format and install it all from scratch considering that there is a large gap between the OS versions?

   
   
   
   
   
   • It is advisable to install all from scratch, not because of the "large gap", but because of software being rendered inoperable. If it's feasible for you to backup your data, install from scratch, bring back the data, and re-configure everything, then I guess a fresh install is better. But again, an upgrade is much less of a hassle =/.
   
   

In any case, always backup your data before an upgrade.