So my plan based on reading was to get a mini pc and a nas. But then I realized... what is the best way to connect them. So I started doing more reading. And I confused myself.

So a NAS has it's own CPU and such, and other computers can talk directly to it over the network. But if I am using a mini pc to run the server, then I assume I would want a really fast direct connection to the storage. So it seems like I would want the NAS to be on the network as well as directly connected to the mini PC. And of course the mini pc would need to be on the network as well. Stuff I saw about connecting them directly seemed to pretty much use the Ethernet ports and a crossover cable. So that would mean that both devices would have to have two Ethernet ports, right?

And the bonus question is, would it just be better for the NAS to really be a dumb DAS for the mini pc instead?

Edit to summarize: For having two devices, the consensus is that LAN is good enough (just make sure you have a decent switch between them). A few like doing it all on one device for a variety of reasons.