And a very short update: 4 and 5 were used for the water. 6 will be used for electrics.
Especially the water is perfect: after 2 adjustments, all the pipes are on the wall, WITHOUT being an sprinkler-installation 🙂
Joost, my bro, came over to help yesterday. He is a certified electrician, and is capable of working HARD 🙂 Thanks mate!