Re sytems, I suggest keeping everything as simple as possible. It just has to be effective, efficient....and reliable. No use having something 'clever' if it does not work easily, all the time and without breaking
I bought my boat with adjustable 12:1 forestay (dont see why you would need 32:1) but as my shrouds are pinned there is little benefit except for ease of rigging which is nice. There is not enougth range in the forestay adjuster to rake the shroud pins on the water. By choice I would have a fixed forstay with boat-braker to reduce weight and keep it simple.
I think adjustable uppers are a good idea but I dont get to hung up on the precise setting, it's a dark art, nobody really nows. Adjusters dont have to be heavy as 4:1 will crudly suffice, as per RS800s.
I have D1s, but not D2s, for better or worse(?), might lose some central mast support but if I can get away with it, I save windage and weight.
Definitely need control lines lead to racks so adjustable whilst wiring. Amidships is more convenient and avoids going forwards when it is scary to do so. As long as they are across ther boat and not fore/aft trip hazards then I think that is OK. I have sailed Kevin's SK4 and stepping forward downwind to uncleat the T-foil because the nose is digging in feels a bit unnatural - scary!
In RS600s rig tension is not critical, just like windsurfs dont use it. In Cherubs with spreaders, jib luff, jib slot, it is more so.
I have a string only 6:1 T-foil adjuster with the downside that one of us has to bend to reach it when maybe we least want to. As it is simple and it works I will stick with it. A twist grip you can adjust without moving seems more ideal.