You are spending too much time wanting to make it perfect. Leave them be. Here is a nice little guide that will provide you with some good background reading to fill your time. It's a nice little primer. Marijuana Cultivation - Wikibooks, open books for an open world

How big are the holes? A little soil loss is fine. The soil immediately around the holes will dry out more quickly. That doesn't mean the whole cup is dry. You can spray the sides if you like but I don't think it's needed. Oh and don't handle the cup as that will agitate the soil and encourage loss for sure. Spray 1x / day to get them rooted (soak the top part of the soil around the seedling with enough water to reach an inch or two into the soil - not much). Once they are up and running set your water schedule to every 3 - 5 days. They will need more water as the get bigger. They will let you know if you aren't giving them enough water (wilting). And as we've both been saying, no added nutes needed. Just up-pot every 3 - 6 weeks depending on the length of your veg cycle.