What means DE version in CoD Ghosts?

Germany version aka low violence. I think that it can indeed be played anywhere.

DE is an Abbreviation for Deutschland.

DE=Deutschland=Germany
Nobody knows, since there is no USK rating for it yet afaik. But probably you will miss the zombie mode and maybe some ingame things if there are any (like the Moscow level in MW2). Also this version will activate everywhere while the ROW version may not activates in Germany.
Languages​​: English, French, German, Italian, Spanish, Dutch, Portuguese, Russian, Swedish

"DERP"

Nothing good in terms of video games. Expect cuts or other "modifications"

People with the german version of Call of Duty Black Ops could only play online with people with the same version. Not sure if the same principle applies to all DE versions of CoD.

Means stay away.

If it's a separate DE version, it's definitely censored in some form. If you're unlucky, it comes with German audio only. If you're extremely unlucky, you can only play with other players on the censored version, although that would be a first for CoD as far as I know. They're probably not gonna do that.

All of these things have happened before (Black Ops for example is censored + German audio only) - there's no standard or limit on how much a DE version can screw you over. Avoid like the plague.

de = cuttet version you need for a german uncuted version a player from switzerland or austria who buy you the game