For one thing, Tiff is not on any level what I would call a typical American. She's not what I would consider a typical person. I don't know any other genius geneticist anime-fan martial artist marksman model-level beauties, do you?
ah yeah we're going to use live rounds to shoot a balloon above your head and make it seem dramatic... >_>, <_< i dunno about you but really?
They aren't human, so no lives are at risk. It all makes sense if you don't think about it.
Just like Sora No Otoshimono: happy, lucky, funny... and then 5 episodes in BAM!, shit gets serious and punches you in the face.