Oh, dear. I don't know if you can escape the army thing... being a citizen, you know.

But I am sure you can opt for civil service instead, which is a great invention, right?
I think you can do that parallel to the studies... working on it part-time, over a period of I-don't-know-how-many-months.
Go and apply for a TUM master in computer science. But, quickly, because deadlines were in May, not in July, as far as I know!
The fee for one semester used to be something like a bit less than 600 Euros, last year, but otherwise, I think it is worth the money. In other "Bundesländer" it is less, as far as I remember. Some of them even got rid of this burden, this year... was it Hessen or Rheinland... can't recall... read it in the news a few months ago, this spring.
You will meet many strict German IT prof brains over there, but it might prove to be a great learning experience even if your grades will be a bit "German-scaled".
With or without citizenship... err.. whatever, you know. It doesn't really make a difference as long as you're a student. All foreign students are treated in a nice way and with lots of respect and support in Germany... at least, that was my experience. And, even after you graduate... I don't know if it really matters...
Well, if you already have the citizenship that is good because you won't have to apply for work permits and the employer doesn't have to justify why he picked YOU instead of some "citizen".