Yeah sharks don't like the taste of people but they generally have poor eyesight so they mistake surfers etc splashing on the surface for food or as you say just curious.
That's not good, I actively try to avoid realtek cards since they are unreliable in linux. I have an asus board with an Intel nic but I haven't had these issues.
Unless you have use case for that much horsepower I would suggest, like others here, buy a mini PC as a start and if you need more down the line buy a second one. They are cheap, fairly quiet and don't use much power.
That's not why it's repeated a 1000 times, it's so when you actually do want to buy something in that category you're more likely to buy theirs because it's familiar.
yeah I wouldn't trust a usb enclose