For res I used 3 60L tubs for each week of nutes and one 200L Res for all the RO water. Each day I would feed the plants nutes in the first hour of the lights being on and I would use a 5gal bucket , I would fill out of the 200L tank, to water within an hour of lights off. So I did all my feeding with the lights on, once at light on and once just b4 the lights turned off.
You ask about slabs? I hate them! If you are growing vertical it makes sense, but for standard growing I prefer to be able to remove individual plants if they are not healthy. If you have a plant that dies in the center of a slab all the plants will suffer. Individual rockwool squares are much preferred.
For veg I would take my cuttings and place into 2" rw cubes, root in 7 day approx, veg for 2 weeks by placing each cutting cube on its own 8"x8"x2" rockwool square and feeding by hand each individually. When I transplanted from veg to flower I would place each plant on another 8"x8"x2" rockwool square.
As for work load, the perpetual harvest helped even out the labor intensive work like harvesting, cleaning, clipping so I wouldn't get overwhelmed cutting down everything at once. Doing a small chop every 3 weeks beats a big one every 9 weeks and I think my yield improved because the plats along the sides of the space were not shaded by the younger plants in the center row.
For strain, I have been trying to find something with a short stretch and quick flowering. So needless to say I haven't kept my strain constant for too long, trying to find what works best. I would often go 18 weeks of trays, in one stain then toss one tray of a different strain in to compare against the previous.
For irrigation, if you were to feed 100 plants at a time I would get at least a 500gph mag drive pump. Use a 1" outlet on the pump that would go into a 3/4" T. So a one inch line from the pump to the T, and a 3/4" line in each direction. Run the 3/4" line around to every plant making a large circle starting and ending with the T, this let's the water pressure even out so the sprayers close to the pump use the same amount of water as the ones in the vary back, far away from the pump. When using a long straight irrigation hose with a dead end ( like what my system has if you can remember) the plants at the front get more pressure and the ones at the back barely piss out anything. I use 1/4" valves to each plant to even out flow in my system because I only have 11 plants running off the same 3/4"line
I hope I got some of your questions. Let me know if I'm giving complete information or missing key points.