It seems there is no longer a SA three channel doser - and I thought at some point in the past I also used to see a 2 channel SA doser. I know there is the Maxi which is a 2 head SA unit and is cheaper than the 4 channel SA units.
Tank 1 -> 4 channel SA + KHD + another 4 channel SA + IOND
Repeat for second tank.
Is that accurate?
Weird. Yes, you used to be able to buy a 2 channel SA doser.
Yes, I think your equipment list is correct.