I used to do communal birthing keeping 2 females together at all time however while it was working there were losses, moms fighting over babies can get rough.

I now have a birthing rack, moms are alone when giving birth and nursing and it has definitely reduced the losses, no fight no stressed out mom everybody is happy.

As far as bottle I use spring loaded ones which do not leak however I only use 6 of them since everything else is now working with a watering system.
The watering system has a 5 gallons reservoir much better than having to fill up bottle every day. As far as flooding is has happen twice and no loss just some wet rats.