Updating from 2.0.2 German to 2.5 (German?)

Hi all there.
i rund WordPress for over one year. I got lot of “bots” which try to get an account on my blog and so they try to spam (but Aki. stops all).
Now i read that there are severell risks in staying on 2.0.2.
i just installed a new 2.5 for a friend, so thats no problem, but i would like to keep my settings, my posts, and the language of the WordPress.
how can i just “update” my blog?
Therefore: Is there no German 2.5? I didn’t found the german Board for WordPress anymore… is the german Support over?
Can i change the language on another way?

Would like to chance to a new Version, but i dislike the english 2.5 (i didn’t sah 2.3.3 yet, so i don’t know if it is “nice”)
Hope you can help me getting a spamfree new blog ??