Those patch cables should be all you need for standalone Vidiot patching, although you are going to want at least one that’s like 18" minimum so that you can patch the luma out into the second key input - this technique is used in the LZX video tutorial for the Vidiot that’s on YouTube. You could get a pack of cables that has different lengths a few companies like Moog and Make Noise sell those pack types. Oh, and one or two stackable splitter cables, like the small green one TipTop Audio makes. Hosa makes a hopscotch one as well that pretty much does the same thing. You are going to want those so that you can send the audio envelope follower cv to multiple parameters.
That capture card seems solid, though I’m sure other users might have a better take on that.
As far as further peripherals go, I would suggest starting with an LFO so that you can modulate parameters. Some guitar effects pedals have LFO outs, maybe you have access to one. You might need a conversion cable from 3.5mm to 1/4" to modulate the Vidiot. That might be the first place to look. Depending on your budget, Hungry Robot makes a standalone LFO that you can sync to a cv clock - which is never a bad thing. You will need a power adaptor for that, though maybe you have access to one as well. Next step up is Eurorack, where there are a lot more options, and a steeper price point. I hope this helps.