Great, thanks! I will not bother with the AI for this build, nor worry about adding another VCO. I'll also have a look at some expression pedals.

addac do a dual expression pedal interface...

I do have a couple of 1/4 to 1/8 cables - I use them between my mixer and AI. The thickness of the cables bothers me, as I am more used to thicker cables :D

yes some can be very thin and plasticy - you can get slightly thicker ones too usually a bit more rubbery like standard guitar cables - I prefer these ones

Two quick questions, if you don't mind...

1) when would an AI module be useful?

Input modules - if you are always using inputs and want to free up other amplification channels...

Output modules - if you get digital clipping when using an audio interface and regular attenuators are not doing the trick / if you are going to play live a lot and need balanced outputs / if you need balanced/isolated outputs because there is noise introduced by the mains power

2) can you recommend any interface modules for pedals?

AI Synthesis, Doepfer, addac, alm sbg

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities