I missed an episode the week before last, so I'm a bit confused about who it is who got all the walkers into the prison - and why they would do it. Surely, they would just die too then? 
I also found Lori's character very irritating, but was impressed with her final scene and the realism of the birth. I was terrified she was going to give birth to a zombie baby and so relieved when it seemed normal. Cried loads during her speech to her DS. It was heartbreaking. And the bloody door didn't shut properly, so I was constantly worried that the walkers were going to get in!
I agree that Lori would surely have thought about nappies and considered that she might not survive the birth and the baby might need formula, especially as she had needed a Caesarean before. Maybe you don't have time to plan this stuff during a zombie apocalypse though... Even if they do get hold of formula and bottles, will they be able to sterilise the bottles and boil the water safely? Do they even have running water in the prison?
I thought the Governor killed the soldiers because he didn't want extra mouths to feed or any threat to his power. He only wanted weapons. I think he wants the women to service the men and have babies. Am not sure why he won't let Merrell look for his brother though. Maybe he just doesn't want Merrell bringing more men back to the town?
Actually, so much happened in that episode that I think I'm going to have to watch it again. I did hide behind my cardi for the scarier bits, so might have missed some crucial scenes
.