i7-6700k vs. i5-6600k Amongst Other Things

The problem here for me is cost, my absolute max is $1500, so I have a bit of give here, but not much. If I end up having to give up something due to going over my budget, what should I give up? I was thinking the RAM as it's relatively cheap and can be replaced without having to swap out other parts (as long as they're still compatible with DDR4).
Is it better to get a M.2 SSD or should I stick with a 2.5" SSD? The only problem with an M.2 SSD is that apparently the motherboard M.2 slot shares bandwidth with the SATA ports so using it would disable one of the SATA ports (so the website says).
For the PSU, should I get a full, semi, or non-modular PSU? All the reviews I've seen say that Full is better but more expensive, so perhaps Semi would be alright. What would you say would be the best of the tiers to aim for with regards to price and longevity? After reading your post, I was thinking Gold might be alright, but better to know from someone more knowledgable than I.
I assume by cooler you're referring to the CPU cooler and not the Case Fan. Speaking of which, none of the videos/guides that I've come by have said how to install an extra case fan, which I would most likely require for overclocking.

Thanks for the help!

There's a small detail I guess I didn't highlight well enough. I live in Canada, where the prices on everything you've listed are anywhere from $2-$200 more expensive. Therein lies the problem, which is why I've stuck with the build I have so far.
I do agree that the CPU cooler could be better than the one that I've currently chose, however the massive price increase from the current one to the NH-D14 is relatively astronomical, and the current cooler is well rated and reviewed, the only problem with it really is the noise and it may not be quite as efficient. The NH-D14 is priced at $95 in Canada, and the Asus MAXIMUS mobo is actually around $250. If there is a CPU cooler that is cheaper than the NH-D14 but is still fairly good, and a motherboard that is cheaper but still decent, those would be useful things to know.
Overall the price for roughly the exact same machine in Canadian dollars is actually $1815.57. Way over my max budget, and considering that I may have to get a laptop to take notes in class, this won't work for me I'm afraid.
I did use your model to downgrade my PSU from the SeaSonic S12G 650W model to the 550W model so that was useful. I don't plan on using SLI and the size of the case would likely make that impossible anyway, so the upgraded mobo is of no use in that regard but it might be more reliable.
I currently have almost no need for an internal hard drive as the I already have an external one of the same capacity, if I did get one I could get away with a much smaller one because of this.
You may be right about using 16GB of RAM as opposed to 8GB, especially if I'm making computer games, it will also help ensure that the PC will still be able to run games several years later.
The GPU that I originally had was cheaper than the one you've used here and was factory superclocked as well, hence the extra case fan oriented in such a way as to provide extra cooling power as necessary.
I'm not sure if I really want to, but I might have to look at a PC case that's bigger and easier to take apart as well, so that drives the price up too. I'm still looking into that but I'm also still looking to keep the price on that below $100 CAD if possible. The one that I've seen a lot of people using is the Phanteks Ethoo Pro, it looks like it could be decent but it's around $140 CAD. I guess I might have to make do with what I currently have at that price though.

Thank you and I appreciate your time and effort in helping a novice PC builder get his act together!

I may need the i7-6700k for my game design, otherwise I agree.
Do I really need an internal HDD? Especially since I already have an external one, though that doesn't help with the installation of programs.
Why use the Gigabyte GTX 970 vs. the EVGA one that I had originally picked? The EVGA one is cheaper, and already superclocked.
I've been looking at other mid-size cases and apparently the Corsair 200R is also rated quite well. I read that there were cooling problems with the Shinobi, so I was wondering if I paid $20 more for a better case, I could skimp a little bit on the CPU cooler and get something under $50. Extra cooling is never a bad thing but do you think it would make a difference?
Other than those, I think this build is, in theory, coming together quite nicely!

Thanks again!

The 200R is $70 in Canada, and upon further searching I also found two other cases which could be just as good and a little bit more inexpensive to boot. One is the "DEEPCOOL TESSERACT SW Mid Tower Computer Case with Side Window and 2 Blue LED Fans SGCC+PLASTIC+RUBBER COATING" and the other is the "DIYPC Solo-T1-R Black USB 3.0 ATX Mid Tower Gaming Computer Case with 2 x Red Fans (1 x 120mm LED fan x front, 1x120mm fan x rear) Pre-installed". The latter is only $5 cheaper and apparently some of the reviews I was looking at said it looked cheaply made and that it might be a bit too small for some graphics cards, but I'm pretty sure most of this was based on the limited available data. Only the former case was actually reviewed in writing and video to my knowledge. Both however are recommended by credible channels on Youtube, the Tesseract was reviewed and recommended by HardwareCanucks, and the latter was recommended but not reviewed by Techsource, but it was used as part of a budget build video by him and seemed to be roughly the same as the Tesseract. I've currently chosen the Tesseract as it was the only one of the two listed on PCPartPicker.ca, but if I'm shown enough evidence aside from price I might go with the Solo T1-R. Both are listed on Newegg.ca so I could get either one. What do you think?

I just looked again, and I happened across the Zalman Z11 Plus. The few reviews that I've seen of it are mostly good, really the only issues with it are the molex cords for the two side mounted fans and the two front mounted USB 3.0's are just extension cords that hook up to the motherboard. While I'm not sure how to deal with molex cables, the extension cable shouldn't be too bad. The case also happens to be $39.99 Canadian, so that seems like a good price and from what I can tell it's actually bigger than the previous two cases. Do you know much about this case, you might see something I don't. So far though, it's between those three cases. Which of those three cases would you pick?