Извини, ты из Германии? Should this be accepted? Or should this question always be asked using formal you?
Your sentence is correct.
Извини and Ты sound unnatural together in this sentence.
I also wrote ты instead of вы. Thinking about it, if the speaker does not know where the person he /she is addressing is from Germany or not, they are unlikely to be friendly enough to call each other ты!
It could be used with a child, or among children. Certainly not between adults. (Well, maybe between adult who became friends in a pub over a few drinks.)
It looks like ты should be accepted
Why not Германию
Из requires genitive.
Германию is accusative.
Извините меня, вы из Германии? - it ain't correct
Yep, the favorite sentence of the germans on their holiday -_-
(Beeing german myself i'm allowed to say this, I think ;-P)