The reason that the Giulietta act ought to come after Antonia is that the music from the Hoffmann/Giulietta duet reappears in the Epilogue, as if Giulietta is still in Hoffmann's head. I'm fairly certain that Offenbach wanted the acts in that order; the reason that Antonia is often performed last of the three is because the Antonia is usually a bigger star and has more to sing than the Giulietta (if the roles aren't performed by the same singer). Plus the end of the Antonia act is much more dramatic.
Calleja - yes, I heard lots of fluttery vibrato ("bleating", some might call it) on Saturday. The opera seemed very closely miked on the radio (I could hear Levine turning the pages of the score at some points), but, even so, I had to turn the volume up quite a bit to get it to the level of sound that I normally get from BBC opera broadcasts.