Well. You're on the right track.
A common timing source is a good first choice. A master clock could be something as simple as an LFO or a dedicated clock module. You can use a dedicated clock divider if you wish. But a good alternative would be a Pam's New Workout or a Temps Utile. They can divide (and multiply) a clock as well as perform other duties like trigger sequencing, Euclidean patterns, etc.
As far as mixers, you'll want at least two... both should be able to handle CV AND audio.
The quantizer is always a good move. So are effects like wavefolders, waveshapers, distortion, general effects (reverb, delay, etc.), and even distortion modules.
A dedicated sequencer to centralize control over all of your desktops would be nice as well... especially if you're performing or triggering things live.