Congrats on the litter!

As far as the male not getting the job done. Sometimes its the male, sometimes its the female. I have a 1.2 group right now and so far only one female has had a litter. The other female is not looking pregnant at all.

With the aggression in the beginning, are you sure the mice that got chewed were female? I've never had females cause damage like that. A little squeaking, some rolling around, that's about it. No blood. I only have gotten bloody fights from males who are around females.