yes, its like styptic powder but not as strong, use a qtip dab blood then put on the cornstarch
humidity for lockdown should be 65-70% it will increase as pipping/zipping happens so right now since eggs are open it would be around 80%, but any higher for too long could cause oxygen in the air to...
use a qtip with warm water and moisten the edges of the shell so it runs down behind the duckling, make sure not to get it in the nostrils of the 'ling
if you decide to peel more of the egg it may lose some fluff, but just keep an eye out for blood, and have corn starch on hand if needed to...
i think you have them open enough, so long as they can breath and their bills are clear, they will probably be out of their shells when you get home
Good Luck and keep us posted!