The Intellijel quad VCA can be used to mix. But then you lose some functionality as a VCA. If you're doing ambient stuff with stereo panning involved, you'll want to run your signals into a dedicated stereo mixer at the end of the signal chain. I'd strongly suggest a stereo mixer with aux sends. You can get away with mixing your signals in an external mixer, but then you have to contend with eurorack synth level signals going into a line level mixer. Depending on the external mixer this may or may not work out well.
In Eurorack, you'll mix your final output as described above. But you'll probably also use other modules to mix/attenuate CV, sub-mix audio like your percussion or a combination of oscillators as a complex waveform to go into one filter, etc.
I'm using the Blue Lantern Stereo Sir Mix A Lot because it's inexpensive and has a decent amount of features. You'll find other modules like the Roland 531 that include headphone outputs as well as a stereo line level output... but no aux sends. Happy Nerding also makes stereo mixing modules as well.
I don't have the Zadar. It's a quad envelope generator. But I don't know if you can get traditional envelopes out of it controlling A,D, R times and the sustain level independently. The Maths can function as a dual attack, decay envelope if you trigger it. Or can provide attack, sustain, release envelopes if you run a gate into the non-trigger inputs on channels 1 and 4. An alternative to the Maths is the Befaco Rampage. There's a lot of overlap between the two but some nice subtle differences.
The style you cited as an example is heavily dependent on reverbs, delays, and other effects. A big part of the sound is the effects. the Disting has reverb, delay, etc. But it's a jack-of-all-trades and a master-of-none. So you may want to look at modules like the Z-DSP or 1010 Music's Series 1 module which gives you access to the Bitbox, SynthBox, and FXBox firmware.
I don't think you'll be able to generate the rich palette of your examples on your beginning set-up. I would go with what you have and see how far you can get with it, learn a bit more about your gear and your tastes and expand slowly.