press and seal can come off ( i took mine off already due to have the incubator humid as possible to begin with.) I got 86% humidity in the incutbator itself and it so humid in the egg containers that I got to wipe condsation off.
as for cutting eggs I say should be find with out adding the water. I never added to the one clutch I hatch out about 2 years ago. then again I cut them at the advise of a poster cause they had dented and were still hard at day 54. ( stupid me forgot to add water to the mix near the end, but they all hatch fine. )
plus if you add water could drown the hatchlings, or cause otherissues if it not the sterile kind ( like IV solution.)