I can answer a few of those...
2) Thunar is a fine file manager. I really like it for xfce. If it isn't your flavor, xfe, nautilus, konqueror (not sure if it's still around much), pcmanfm, are all pretty good ones. There was one based on Norton Commander (I think it was called Midnight Commander...not sure) that was pretty good. There are lots of options, just google linux file manager, and lots of choices will pop up. I stick with Thunar though, just because I like it.
3) If you're using xfce, sometimes menu shortcuts don't get put in the right places. If it says gedit was removed, you can always reinstall it using:
apt-get install gedit
As for why no shortcuts for nano, it's because it is a command-line text editor. It is really easy to use, as far as command-line editors go, as it has a very good interface for people like me who aren't smart enough to use vi/vim or emacs. I could never get the hang of them, but nano is really easy to use for me. But to use it you have to open a terminal or a console.
There are dozens of text editors, and there are always battles about which is best. I really don't get involved. I just ignore the fighting and just use what I like. Here are some graphical ones I like and use: gedit, mousepad, leafpad. Like I said, there are LOTS. I won't say what is best, because it just depends on your style of working.
5) Ask away! If there is something in the wrong place, I'm sure some gentle moderator will leave a friendly reminder and/or move the thread.