[Build Help] Looking to upgrade CPU. Need help w/ Mobo suggestions & cooling/PSU questions.

Hi, everyone. I got great advice last time I posted here, but I wasn't able to implement it, because my timing belt blew - so my CPU $ became new car $. But now I have taxes, as well as a few new concerns.

First, my stats: I currently have:

• AMD Phenom II 555 Black - 3.2 Ghz Dual
• Radeon HD 6970 - 2 GB, PCIX2
• 8 GB DDR3 1600 (I believe it's 4x2).
• 530W power supply
• This Thermaltake case
• 4 7200 RPM SATA HD - 1 TB, 3 TB, and a pair of 512s.
• 1 IDE HD - 32 GB

Budget - $400 is my hard limit. $350 is my preferred price.

The four things I most want to play on my upgraded PC - Fallout 4, Dwarf Fortress, Just Cause 3 and Touhou. I'd also like to have enough overhead to run OBS and Kerbal Space Program at the same time.

I don't overclock my processors.

I think the realistic choice is either the 3.5 ghz 4690k or the 3.5 ghz 6600k, (about $240) but the 4 ghz 4790k is really tempting. Is it worth the extra $100 for the types of games I play?

As far as motherboards - my main concern is shielding, and I don't know how to look for quality there. My current board has constant crackle, and squeaks when I'm using the USB. Also, I'm planning to stick to a DDR3 board. Is DDR4 significant enough yet to consider switching? (In terms of DDR3 drying up. obviously it's faster.). This one was one of the most rated in the $50 range. Is that ok, or is there something obviously better for a similar price?

As far as cooling, my current CPU has been starting to see temp creep (usually no more than 54 C, but occasionally spiking to 58 in some games). All the Intels come with Heatsink & fan, but I'm now concerned about whether it's enough. Do I need to add aftermarket cooling?

And lastly, is 530W going to be enough power, or should I err on the side of caution? Newegg says 680W, but I've tried a few calculators and seen anywhere from 420 - 720 W.

Thanks in advance.