Germanation questions

[Rye]

Hello all, yet another newb here, with yet still more questions.

I've read through a ton of material on here and probably missed the answer to the question(s) I am asking, and for that I apologize.

I am starting a basic Kratchy system in my office. I got all of the essentials and assembled. I soaked my rock wool to stabilize the ph, then dropped seeds and set the cubes into a 1020 tray to germinate. In the tray, I added a 1/2 gallon of light nutrient water. My Kale has been sitting in this for about 12 days now. It's 2 inches tall and starting to throw the their 3rd leaves.

Question. I've read here the rock wool isn't supposed to sit in water, clearly my first mistake. I can fix that tonight, and let drain/dry. Does the wool not dry out and fail to provided the needed moisture to the plant?

Second, when I set the rockwool into the baskets I am supposed to bring the water up to the bottom of the basket just touching the rockwool, or do I fill to 1/2" under the basket and let the roots reach down to it?

Thank you for your assistance in the first of the million or so questions to follow.