How do you intend on mixing audio signals and attenuating/mixing CV?
Output?
Do you plan on having a clock source?
I would have a couple of traditional ADSRs in the rack even if you're going to keep the Zadar.
Noise sources?
Additional utilities will eventually be on your list.
Plan to have a bigger rack than this. The amount of HP you've left yourself just won't do. Eurorack systems grow.