Hi Glenn, nice selection (and rack name). I agree you could use some more cv mixing/manipulation. A Xaoc Samara II (offset, attenuate, invert, s&h, logic, mix) and a Frap Tools 333 (mult+mix) might be helpful. That Ladik M-174 mixer seems rather large to me. Maybe get a smaller Doepfer A138s instead? Now you should still have some space left. Which is good as there are a bunch of potentially interesting things missing (as far as I can tell), like a wavefolder, comparator, a small utility filter etc. Look into those once you're familiar with what you have.
The Ladik output modules are attentuators already. Albeit with a fixed attenuation level. You should be fine. Personally I prefer balanced outputs, but these consume more space (and money). And you'll find lots of people disputing the need for dedicated output modules anyway. So, IMO these are a good choice to start with.
Cheers, Chris