I've loved DWC for many, many years now.
Good catch on the oxygenation thing, cannabis plants require a bit more than most plants. Run your pumps 24/7 for best results, especially later on in flowering when oxygen demands increase.
As for nutrients, I don't know anything about the brand you're using. I would recommend looking for others in hydro who are using it, then seeing how this information applies to your situation.
Your roots look good in the photo. I don't see a mention of solution temps, you'll want to keep it between 65F and 69F. I put airpumps in cold a/c air, then use aquarium heaters to keep the temps at 69F.