Need help newb

Should I cover the cubes or tray so not to get light and make holes for the stems? You don't have to cover the cubes but you can do. I would wait to put them in the clay pebbles (or whatever you're using with your hydro system) until the roots have taken hold a little more, but you can transplant them earlier if you're having difficulties with watering. The roots are 4/6 inches long, how much watering should I be doing if humidity is being controlled at 75? Water them whenever they need it. You want the rockwool to be moist, not dry or soaking wet. How wet should the blocks be? Wetter than they are now - the ones in your photos look really dry! Give them a good watering and then wait for the plants to suck up >50% of it before you do the next one. How strong b52 and sensi grow should I use per 1L? 1ml Grow and 2ml B52 per litre of water according to the instructions - but I would go with half of that on the first feed. It also says you should use Micro and Bloom at 1ml each - you can do what you like, but keep an eye out for deficiencies that may appear as these things are usually formulated by the makers so that you need to buy the whole collection. Good luck, and good job bringing them back from the dead so far! :)