Well, I only recently started my breeding, but I have 19 (it was 20) fuzzies and older pinks all together in the house with all three adults caring for them. My girls had their litters two days apart, and I left them totally alone for at least one day after delivering. It worked, and now they are being good little mousy parents.

As for picking them up... they can vary just as much as rats, but generally are just as nice. The only big difference is that you can't just hold them on your arm as easily as rats and should keep hold of the tail as you hold them. After a while, they'll get to know you and will just run around on you without trying to jump.

I personally wouldn't separate the mice, because you would be hard pressed to reintroduce them unless you put everyone into a whole new (read thoroughly clean) enclosure. For me, it's just easier to leave them all together and separate the babies by sex once they're weaned. I don't worry as much about back to back pregnancies either with the way my girls chase off the male when he tries anything with them.