Night Owl / Mephisto

18 hours is good enough gives them time to rest and if ur humidity is over 50% And 95% humidity seems to much personally I don’t put domes over my plants

Put a hole at the top of your domes to allow good air exchange. Will bring the RH down to a more reasonable level If it worries you that much. Otherwise follow the great advice you already have been given

You should be fine mate. Just remember to let some fresh air get to them every so often and within 2 weeks you will find you don't need the cups anymore. Before you take them off permanently try giving them more and more time to adjust to the environment.

When the leaves point up like that its usually a sign of to much light, as long as the leaf color by the edges and tip are green your all good. I would raise it a little and see if they flatten out. Its usually only a seedling thing as they get use to the light intensity quickly. Happy Growing

Looks fine if it keeps stretching light is too far or too dim.

Do not panic. Your sprout is setting it's first set of true leaves. They often can look less than perfect (being born is hard). Over the next couple weeks the plant should grow and look more "normal". Also, do not freak out when the first two cotyledon false leaves turn yellow and fall off. That is normal.