Oooh! I love Blood+! I think it will be a good anime too, and I love the opening song as well. The thing she fights are Chiropertans (sp?), and I suppose they are monsters. However, the US military calls them Mouses, so I dont know.
I think Saya's adoptive father has the saddest life, he's always getting hurt. Also, Saya's 'brother' loving Saya is so much like Shinogu loving Hatsumi in Hot Gimmick, its uncanny XD