Regarding the chicks that didn't hatch: it depends on what they looked like when you opened up the shell. Google 'chick shrink wrapped' photographs and see if they look the same.
During the cooler days recently, if the humidity outside wasn't high enough it wouldn't have been in the incubator either. I have found that incubating dry with the Brinsea
in my house leads to disaster, but it entirely depends on your environment.
Hope the 8 are all doing well