Hi Nickgreenberg,
Regarding your first question: Yes, there is a huge difference in quality regarding patch cables. For example take Vermona's patch cables or those from Cordial the CPI ZZ series whereby is the length in metres; these two are great patch cables but bloody expensive. Then on the other scale there is for example those patch cables from Endorphin.es, which I expected would be good patch cables but I had to return them, extremely thin cables and also very thin moulded mini-jacks. And of course then there is anything in between from fair till good. Endorphin.es is just an example there are more bad examples (like those cables that come with some of the Behringer equipment, those cables are also not top-notch stuff, but to my surprise at least a slightly bit better than those from Endorphin.es). I am using quite a bit of Make Noise patch cables, those have moulded mini-jacks too however their cables are a bit thicker and if I am too lazy to make myself the cables I usually buy those from Make Noise, kind of fair quality I guess.
Making yourself patch cables is here perhaps the best option. I am using a rather thick instrument cable from Cordial and using Neutrik mini-jacks for my CV cables (I use blue to differentiate) and I am using even a bit thicker black cable from Cordial in combination with gold-mini-jacks from Amphenol for my audio patch cables. But it's a lot of work to DIY, so if I am lazy I buy those from Make Noise :-)
That are my 2 cents, kind regards, Garfield.
Edit: removed a typo.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads