new here, questions. starting medium, seeds.

[KlondikeRoad]

New to hydroponics, now have several plants going in a sun room here in WA. Brought young and self sown chard, spinach, kale into house, washed roots, and using the method with no air flow.
Questions- I am concerned about rock wool and using that as a starting medium for transplants into soil garden. Does it compost well?
Real sheep wool- we have a farm, and an abundance of sheep wool. Has anyone used that as a starting medium? (have these plants in a bit of it mixed with the clay beads now)
seeds- going to set up a system with air in a tote- what are the best lettuce seeds for this? Does it matter? Will any buttercrunch lettuce do? (or red sails, leafy lettuce)
Has anyone tried the rockwool in a raw form? We live close to Grand Forks BC where they manufacture rockwool, can probably go there and purchase rockwool in a loose form. Would that work?
Have always been a soil gardener-