1 Intel CPUs are way better than AMD ones in editing and things that are CPU intensive. On the other hand AMD cpus still are great in gaming, but not better than intel ones. Intel cpus are also more expansive
2 not sure about this, video editing uses mostly cpu cores am i right? i'll leave this to another redditor
3 When choosing a case the thing that matters most is the look of it. You are probably going to see that case everyday and if you don't like it it will be a pain in the ass. So do you like the look of that case? It's expansive because it's more on the premium side of cases, you could spend half of the price but you won't really find something that beautiful or well built. Look into the 200R, it's half the price and still has a minimalsitic look, if you don't want to spend a lot on a case this one is great. Also the Bitfenix Shinobi. I was deciding between those low end cases too, then i saw the Fractal Design R4 and i decided to just save more and get that windowed babe, a case will probably last a lot of years and you can use it between builds, so i decided that saving some cash for a awesome case is a great idea.