Couple suggestions would be to go for Skylake instead of Haswell as it's pretty much extra performance for free (relative to Haswell-R) and you get more future-proofing because DDR4 is the new memory standard.
Also, I'd heavily recommend waiting until July and picking up an Rx 480 instead of the GTX 960 as it will be significantly more powerful for the same cost. You can still build the PC and use integrated graphics until then.
Couple suggestions would be to go for Skylake instead of Haswell as it's pretty much extra performance for free (relative to Haswell-R) and you get more future-proofing because DDR4 is the new memory standard.
Also, I'd heavily recommend waiting until July and picking up an Rx 480 instead of the GTX 960 as it will be significantly more powerful for the same cost. You can still build the PC and use integrated graphics until then.
Yes, the 6600k is the Skylake counterpart of the 4690k. Also, because Skylake uses a 14nm architecture it is more power efficient, meaning you should be able to get better clocks (I'm assuming you're buying an unlocked CPU to overclock).
The Rx 480 will simply have better performance. AMD is at the moment advertising it to be roughly as powerful as a GTX 980 (although those claims will be tested when it comes out). It's also more power-efficient than Nvidia's Maxwell cards such as the GTX 960.
I'm assuming NVidia will try to make their gpus better to counter the Rx, should I wait to see if NVidia do or will they not?
Also, will there be any obvious bottlenecks with this build.
Nvidia have already released their new Pascal cards. Nvidia just started their new generation of cards with the higher end cards (GTX 1080 and GTX 1070) whereas AMD is starting with the affordable stuff like the Rx 480.
The Steam overlay exists exactly so you don't have to go to separate windows to access Steam features. Honestly I'd say that not having quick access to Skype isn't too bad a trade-off for having a nice 29" Ultrawide monitor.