But he is using the Flora Series of Micro, Bloom and Grow. I'll tell ya, many growers have just used 3ml of each throughout veg and flower, or 5ml of each. That mix will grow some fine plants. If you want to fine tune it some, you can use twice the Grow during veg, and twice the Bloom during flowering.
No need to mist seedlings. Just keep the medium moist, the heat mat will dry it out fast.
HTH