Hi doc11
I'm also not that long on the forum but let me help you with the knowledge I already have.
You will need an output module that brings your signal from synth level to line level I use the Bastl Ciao!
You will need a mixer to mix your signals together. HappyNerding offers some good mixer modules or since you are tight on space the 2hp mix you can use a couple to mix CV and audio signals.
I don't know all your modules and how they interact with each other I leave this to the experts but here you have some basics!
Good luck!