1.
Backblaze's hard drive reliability report painted
HGST/Hitachi in good colors.
Fake edit: yeah, you've seen that and others have already brought it up.
2. There's no telling what future graphics cards may require in terms of wattage and amperage. The GTX 970 will probably run on that 450 watt power supply, but it will be cutting quite close to the limit. Generally for power supplies, you want to leave a bit of breathing room not just because of future upgrades, but also because power supplies are more efficient, run cooler, and last longer when they aren't operating right at their maximum capacity.
Unfortunately, when you want to go with a such a small and specific form factor like the Silverstone RVZ01/ML07, you need small power supplies. No one else really makes any comparable power supplies, so they can get away with charging $130 for a 600 watt power supply. At least it's a quality power supply,
reviews show that much.
4. No, the Corsair water cooling kit is completely self-contained and is pre-assembled. You do not need to put anything together besides the metal mounting bracket, and there are instructions for that. All you need to do is put the pump on top of the CPU and mount the radiator with a fan to the ML07 side panel fan mount. I won't lie, it could be a tight fit, but others have done it and it is a recommended part in the
Overclock.net Silverstone small case owner's thread. We did have a guy in the old PC build thread who was unhappy with the GeminII M4's cooling performance, and IIRC he had either the RVZ01 or the ML07B.
Actually, I also have another recommendation to go with the water cooler. Instead of using the included fan, you may want to buy a slim cooling fan for the radiator, like this
Silverstone slim 120mm fan ($14) because the spacing is cramped.
5. There's very few PC cases that pull off the game console size and look and have the performance to match. There are cube style PC cases that are also compact and will take a standard power supply, but I'm guessing you already considered those.
6. I'd wait it out to see three things: reviews of the RVZ02, news of Intel's new processor line, and the AMD R9 390/390X series, all of which should be coming in a couple of months. The GTX 750 Ti is a great choice for gaming at 1080p/medium settings or lower, and it'll go with the 450 watt power supply just fine.
