check out this journal... lots of good ideas.. it kind of reminds my of your set up but he has a DWC set up you could build cheep as well then move your other plants to the DWC set up.just an idea for you to think about..
ask all of the questions you have. i do not mind at all... in the beginning of my grow i used a drip system to water the top of my rockwool. i used that until the roots were exposed to the spray. i used a small pump a small section of 1/2 in hose and connected that to a drip manifold (i got it from Lowes) that distributed the water in 1/4 in tubes to the tops of each plant's rockwool. i bet you could tap a small 1/4 inch line directly to your spray system without any problem. i could post pictures if you need to see what i am talking about.