How to use a "real" editor: Oh ffs, c'mon. Most people in their daily lives will never need Vim or Emacs. And let's be honest, if anything, they're way better off using something like Nano, that has a short-cut system they are likely more familiar with. There is no need for them to go through the learning curve of a tool like Vim or Emacs.
Vim is my IDE. I develop entirely and totally on the command line, devoid of any GUI management or development tools.
Just because the tools are available through a GUI doesn't mean that the kids will use them the same way. I learned about as much about the above topics in a week of doing server admin stuff as I did in years of running Ubuntu with GNOME.
>I didn't (know) Emacs and Vim does not have GUI version.
Despite have GUI versions, the likelihood that most kids would use them is roughly 0. If you give kids a GUI, they'll learn how to use Microsoft Office/OpenOffice and maybe notepad/gedit. If you give them a command line, they'll probably learn nano -> emacs/vim and then use LaTeX when they need to make something they'd typically use an office suite for.
Available from most GUI file browser.
> -environmental variables
Available on GUI.
> -package management
Synaptic, or some package management GUI.
> -what a daemon is
There's GUI for Service management.
> -possibly how to use a "real" editor such as emacs or vim
I didn't Emacs and Vim does not have GUI version.
> More importantly, this kids will never be afraid on the command line
That's only important if you value being able to use command line, it's circular reasoning.