1) Rockwool holds a ton of water and for someone starting can be real easy to overwater. I had found that for me Rapid Rooters with Hydrtron was the ticket.
2)During entire grow keep ur PH between 5.8 & 6.2
3) Digital meteris best. Test strips will get you close but not exact.
4) I use to flood mine for 15 mins 4 times a day (every 6 hours)
Oh and welcome to Hydro