I watched this one last night. It's a mixed bag. There are a lot of really good scenes - Picard and the children in the turbolift, and especially on the ladder. LaForge and Crusher opening the shuttle bay doors. Worf delivering the baby is hilarious.
But then we also have one the more epic failures of scenes in TNG - Geordi having that plasma conduit exploding in his face and not being able to see the heat. When you think of all the people that must have read and edited that script, and no one catching it, not the Director, not the actors...wow. This isn't some obscure Trekkie lore issue. They all knew Geordi could see heat, and...just forgot.
As to the question of how many died - they were uncertain if sensors were reading right, so they didn't know if the sections they scanned really had no lifeforms.
And since there is no mention of deaths other than the Lt. on the bridge which we saw, I'm thinking she was the only one.