Questions[.desktop](ubuntu)

I am working on this pre-existent .desktop file and I have a doubt:

The file content is:

[Desktop Entry]
#Icon=connect-data-space
Icon=XCloud
Categories=Utility;
Type=Application
#Exec=/usr/share/ConnectDataSpace/appl/launcher.sh
Exec=/usr/share/XCloud/appl/launcher.sh
Name[en_US]=Connect Data Space
#Name=Connect Data Space
Name=XCloud
Comment[en_US]=
Comment=
StartupNotify=true
Terminal=false
OnlyShowIn=GNOME;Unity;
StartupWMClass=ConnectDataSpace
Actions=CheckUpgrade

[Desktop Action CheckUpgrade]
Name=Verifica Aggiornamenti
#Exec=java -jar /usr/share/ConnectDataSpace/appl/lib/shellExtBridge.jar -checkupgrade
Exec=java -jar /usr/share/XCloud/appl/lib/shellExtBridge.jar -checkupgrade
OnlyShowIn=GNOME;Unity;

What exactly does the StartupWMClass field of this file represent?

To the best of my knowledge, all shortcuts in the Unity Launcher have a corresponding *.desktop file. I have one shortcut (for skrooge) that doesn't have an icon. How can I find the *.desktop file corresponding to this shortcut so that I can add an icon to it?

In older versions it was easy to create a launcher on my desktop. All I had to do is right click on my desktop and select the "create launcher" option.

How can I create such launchers now?

Will Unity allow making custom launcher icons from .desktop files or via menu editing system? (Right now the launcher doesn't give the option to "keep in launcher" on all programs.

For some programs I use, I have to make custom launchers or .desktop files.

For instance, daily blender builds are generally just folders with an executable.

In basic Gnome or KDE, I can make a new menu entry with the menu editing system. Then, I can also add it to Docky either from the menu or by dragging a .desktop file to it. Unity launcher doesn't support drag and drop, so thats not a bug or anything, but when I open a .desktop file, it has unpredictable results. Most time it will not have "keep in launcher". Sometime it will have a pinnable item without the .desktop's icon, and if I pin the item to the launcher, it will not call upon the program again after closing it. I've also gotten it to just work with a .desktop file for celtx.

From what I can gather, .desktop files are shortcuts that allow application's settings to be customized. For instance, I have lots of them in my /usr/share/applications/ folder.

If I open that folder in nautilus, I can run these applications just by double clicking its associated file, e.g. double-clicking firefox.desktop runs Firefox. However, I can't find a way to do the same thing via terminal.

If I do gnome-open foo.desktop it simply opens foo.desktop as a text file. If I make it executable and then run it in bash it simply fails (which is expected, it's clearly not bash script).
EDIT: Doing exec /fullpath/foo.desktop gives me a Permission denied message, even if I change ownership to myself. If I make executable and do the same command, the terminal tab I'm using simply closes (I'm guessing it crashes). Finally, if I do sudo exec /fullpath/foo.desktop, I get an error reporting sudo: exec: command not found.

That's my question, how can I run a foo.desktop file from the terminal?