I think you're on the right track. Stages seems like a large bite to chew for your first rack, but if you really want cv control over each step then it might be your best option in a small case.
Zadar seems overkill. I would imagine you will always have at least one or two unused outputs. Also, if you plan on using it at audio rates to modulate mco, then why not go with something designed to run at audio rates? Twin waves seems like a better option. The lfo modes are great and vco modes have a built in quantizer. Now that I think about it, just ditch MCO all together for twin waves, and then you could lose the pico quant as well. The quantizer on twin waves doesn't respond to trigs, rather it just continuously confines your sequence to a scale, so if you went that route maybe you would want to add a 2hp sample+hold to be able to achieve sustain. Or maybe you could just use stages in such a way where the s+h isn't necessary.
Hope this helps.