What a mess...
Out of the 2 psus quality wise (since that was the criteria) the RMx is better, not by much, but it is. As far as wattage goes, that depends on op's needs. For a low-mid OC the 550w is fine, it'll only add @50w (give or take) to psu draw, and thats only at maximum outputs under stress tests etc. For regular gaming habits, 550w will be fine. If Op plans to really push the OC (not something advisable even with an H7) then you'd be looking at closer to 100w added to the cpu, so in that case, the 650w would make more sense. No point in maxing out power draws on the psu, it's inefficient.
The H7 is superior in every way to the hyper212 evo. Not only shorter (fits in a lot more cases), does outperform the 212, has no ram clearance issues etc, but has a vastly superior mounting system. The hyper212's mount is abysmal, not easy to install and quite easy to screw up. I personally quit recommending the 212 series years ago, the H7 or even the deepcool Gammax 400 being far better options.
Windows will work fine on 8Gb. As a minimum recommendation for gaming. However, there's plenty of the more intense games that are making good use of higher ram, some clearing 12Gb of use, especially with higher end cpus combined with higher end gpus. For the price of this build and its potential, 8Gb would be closer to being a potential bottleneck than any other component. 16Gb might be over the top, but it's really the best option in dual channel capabilities.
SSD. Bigger SSDs most always have better speeds, the 500+ being marginally better than the smaller 250+, so there's that. As far as storage size goes vrs performance, that's a toss up. Anything run through the OS will be run at SSD speeds, not the hdd speed. It all gets cached on the SSD through Windows temp folders. So makes little difference to a game stored on the hdd, with its launcher run through Windows. How much of a difference an SSD makes depends entirely on the game, some see considerable gains, others little, and it's more than just zone loading or waiting times, anything used by the game in repetition is also affected, so things like a gun or camo, clouds, grass etc is pulled from the SSD temp cache, not the hdd. But, games are not the only thing stored on pc's, there's also media like photos, music, videos etc that eat up a lot of space. Those files are best kept on hdd.
A single large SSD might see some performance gains, but the offshoot is shortened lifespan with all the extra r/w that that entails vrs having a hdd that'll absorb much of the temp folders and larger files that don't see common usage.
Last of this rant : Intel vrs Amd. Personally, I'd be more inclined to go with Amd. You are now looking at games requiring a 4core minimum. Many games, such as gta:V, BF1, BF4, Starwars Battlefront, any mmorpg with high server drops etc can and do make use of multiple threads, 8 isn't uncommon. While it may or may not make much of a difference, the option is there. The R5 1600 is equitable in performance to a i7-4790k for about the same price as an i5, at stock speeds. With OC and fast ram, it gets closer to the i7-7700k and beats the i7 in just about all the other multiple thread applications, coming close to double its performance in some. And AM4 is brand new, with the i5-7600k you have only one upgrade, the i7-7700k, with AM4, you are looking at at least 3 options just in this generation, and probably 3-4 more in the next generation of cpus. For as good as the i5 is, it's really just a very big carrot, on a very short stick, it's not a cpu id actually recommend now, it's going to be a limiting factor with just 4 threads.