I'm not a first timer or new mommy, my oldest is 6. I would have been livid about the bottle mix up. Especially since you have everything labeled. I mean HELLOOOOO all she has to do is read the dang bottle.
I breastfed my oldest until I became sick with pneumonia and my milk dried up from the steroids and other meds I had to take. Our youngest was actually allergic to my breastmilk and had to be formula fed. Either way both of my girls had to have a specific formula because they couldn't tolerate most formulas and were allergic to some of the formulas. I would have been beyond upset to have my child's bottle switched.
While allergic reactions are usually non life threatening, who wants to put their baby through hives, vomiting and diarrhea which can lead to dehydration very quickly in infants. Especially when it is easily preventable by reading the name label on the bottle!!!! Believe me when I tell you, I've witnessed allergic reactions with my own girls and it's just miserable. I felt totally helpless and like a failure because I couldn't make it better for them.
The center needs to have a better plan in place. Perhaps you could suggest they have color coded bins in the fridge. Each bin is labeled with a specific child's name. Anything for "Timmy" goes in the red bin, "Susie is the green bin, etc. Or just take a bin of your own in and make it perfectly clear...everything for "Susie" will now be kept in this bin to avoid any further mix ups!"
I think the center itself should be taking this far more seriously. I mean for heaven's sake she almost gave your breastmilk to another child. What if she had given your daughter someone's breastmilk instead of formula?
As far as the rambunctious boy is concerned, I think that's pretty standard behavior for the age group. Did the caregiver address the hitting with the boy when it happened? If so then you can be confident that they are working on this issue with him. If not then either she didn't see it or she is too overwhelmed to handle it all.
I think I'd let this one ride and see if it continues to be an issue before I bring it up. However, next time if you are there when it happens maybe make a "Wow, I hope he doesn't hit the baby's in the head like that often. Has he just started doing that? One of the baby's could get seriously injured if he had a toy in his hand?" See what kind of response you get from the caregiver and if you're not satisfied then address it with the director. Your child's safety and well being comes first :)
Peace and Blessings,
T. B