I am a total beginner, any ideas/advices what VCA and VCF would suit this setup? Many thanks for comments...
For VCA you can't go wrong with the Intellijel Quad VCA. 4 VCAs in a single module that can double as a mixer. Very useful both now and down the road when you have more modules.
The sky's the limit when it comes to what filter to use. The most popular "basic" filter is the Doepfer A-124 Wasp filter, which is a 12db basic multi-mode filter, but really any filter you feel like would work for you could be used.
Yep, love the Quad VCA...it also increases function density, which is critical if you're doing a 3u skiff like this. My advice for going further would be to jam maximum function into smaller space (hence the Quad VCA) and save the large hp spans for very specific functions that are must-haves.
As to a filter that fits this bill, my suggestion would be a Doepfer A-121-2 followed by a 2hp Mixer. That way, you get the multimode filter, but with the added mixer, you can combine response outputs for some elaborate sound manipulation, and the whole mess fits in only 10 hp.
But go small and powerful...there's quad LFOs that fit into that Dual LFO's space or less, and those would be better options with the limitation the skiff causes, and so on. Also, see if you can locate a powered skiff, such as the Erica 84hp skiff or MakeNoise's powered 104hp. That way, you take the power off the patchpanel and gain another 4 hp. The more space you can free = more space for possible functions.