Does Christiano's voice (at least in the second anime) sound like a vortigaunt to you?
No Export for You: The PS2 gaiden games aren't going to be released out of Asia. It only features a couple of characters, the cyborg Pia and her handler Earnest. They don't appear in the anime/manga version of Gunslinger Girl.
The Other Darrin: In an inversion of the norm, the second season and OVA feature a completely different Japanese voice cast, but retain the exact same English one with the exception of Hilshire.