The 500R (the link you provided to your case choice leads to your CPU choice)? I certainly like it, even if it is a little bigger than perhaps I needed. It was very easy to build in, which is what I was looking for at the time. The integrated fan controller works well (for the two front panel fans and the large side panel one), and allows for quick changes in cooling and noise output. All in all, I have no real complaints, but then I knew what I was getting, as I read a number of reviews of it first.
The case is a little long in the tooth now, as Corsair are pretty prolific in the releasing of new case designs, so there may be 'better' cases now, but I haven't really been keeping up to date on case releases.
The reason the GTX 970 is being suggested is that it's brand new, its performance is about 25% better than the 770 (comparing reference design to reference design), and it's being released to replace the 770, which is being discontinued. Most importantly, in the US at least, its price on release is $330, which is lower, than the price 4GB 770 cards have been going for (all 970 cards come with 4GB of VRAM).
As to motherboards, well, as your friend points out, you don't necessarily need SLI support, but true, it is nice to know it's there. I built my system with future SLI in mind (SLI compatible motherboard, substantially larger PSU capable of supporting two cards), but in the end, I just couldn't justify getting a second card; there were so few games that I played where an extra card would of made a substantial enough difference, as at the resolution I play at, one card provided me with enough performance most of the time.
My memory may have gone wonky, but I believe you'll need a Z97 based motherboard to get SLI support as I don't believe any H97 board supports it (due to the PCIe lanes issue mentioned previously).