Chicks can go for at least 3 days without water or food. That is why hatcheries can send chicks in the mail without problems with feeding/watering them. Congrats on your little ones! Love those dark eggs! I am hoping my BCM has dark eggs like yours!
I have heard it is not good to remove chicks from the incubator if you have other eggs that are pipping. The change in the incubator is dramatic when you lift the lid. Think of it as when you are taking a shower and then pull back the shower curtain/door. The room fills with humidity and the mirror gets all fogged over and you get cold! Well, it's kind of like that with eggs, but reversed. The membrane inside the shell does a shrink job on the chick inside. So, don't worry about the little chick, they will be fine for 3 days. And, their chirping helps the others to want to get out and play!
Good advice - I found the 3 day rule today. We had one more hatch today - the Welsummer (dark spotted eggs) look like they are on a 22 day schedule. We will give them till tomorrow before we crack the incubator open - hopefully by then what is going to hatch, hatches.