Egad

So I don't do aero type work, but I do lots of rendering.  I would definitely delve in to which graphics cards and drivers can support your work related programs.  I work a number of programs that benefit greatly from CUDA and thus for professional reasons, even though AMD has better price to performance for gaming, everything I've build for work or my home office has been nVidia for quite some time.  I know a couple coworkers who went the AMD route and after a few months of pain, sold the AMDs and bought something with CUDA.  I have some familiarity with CATIA and I know AMD benchmarks well there, but for any other programs that lean on the GPU you might want to ask around.  
 
You may want to consider a GTX 970 or a used GTX 980 (if you can find a deal) simply for the work related programs if they benefit.  Other than that one concern, it looks great.  

Yes in theory, but every DX ever has had a bunch of features that card makers/game developers never quite got around to supporting.  Or features that MS talked up (remember DX is competing with other APIs) but turned out to not really worth being implementing.  
 
There are a bunch of multithread features in DX11 that never really got used to the extent they were talked up.  VRAM stacking, async, etc all sound great when MS talks them up, but we'll see what gets used and what the benchmarks are at the end of the day.  

When is your 1080p upgrade planned for?
 
So the i3 plus R9 380 is a functional combination and should work in most cases, although in games that can't take advantage of hyper threading, you will suffer.  
The i5 plus 750Ti eliminates the core issue and the 750Ti VRAM will be perfectly fine for your current resolution, but 2 GB of VRAM is not very future proof.  Already 1080p games are using more than 2 GB VRAM and 4 GB VRAM is becoming the expected standard.  
 
Now of course everyday that passes, the older i5s get cheaper because of Skylake, the future release of Zen, etc.  So if you bought an i3 now, the i5 should be more affordable in the future.  Of course the same is true for the R9 380, when the next gen of video cards comes out, current gen prices will drop.  If you plan to go 1080p relatively soon, I would do the R9 and i3, just be aware certain games will suffer on it, but at 1080p the R9 will give you more FPS and you have more headroom with the VRAM.  You can look into an i5 or i7 post Zen launch when hopefully older gen prices drop.  If you plan on sitting on your current monitor for longer (say at least a year) I'd do the 750Ti and i5.  Then once the next gen graphics cards are out you can consider an upgrade to a R9 and a 1080p monitor.  

I'll second EVGA.  Great customer service.  Their best 980Tis all ended up going out as Kingpin's but their SC+ is still a very solid performer. 

If you're asking this I have to ask you, what are you doing with a 5960X.

Personally I enjoy writing comments discussion how Team Green is better in this market segment and Team Red is better in this segment, so your purchase should be based upon budget  and what you want to accomplish, not brand loyalty.  Then both sides get angry because I said something nice about the other side and go nuts.  
 
Generally speaking it goes in cycle.  nVidia just got caught with its hand in the cookie jar on Async and the 970 RAM issue isn't that far in the past, so the AMD fanboys are running around and talking like AMD/ATI never lied to them. If only we could all happily come together and agree it doesn't matter what the OEM says, it only matters what it benches.  
 
Although on the green side of the world, "I gotta have a Titan for bragging rights" ensures their side gets some representation in all this.  

October 2016? Intel will have it beat before it comes out. (if they don't have it beat already)

avoid the Asus version and also the 2GB versions
 
the Sapphire Nitro or the MSI Gaming are the best of the lot for AMD cards now

980Ti or Fury X
 
A 390X will get you into the mid 50s for 1080p and low 50s for 1440p and has more overall life left in it with its memory and bandwidth likely.  Plus it leaves more money in your pocket.  

980Ti or Fury X
 
A 390X will get you into the mid 50s for 1080p and low 50s for 1440p and has more overall life left in it with its memory and bandwidth likely.  Plus it leaves more money in your pocket.  

Yes.  I have a GTX 980M and if you're not plugged into the wall you're either using nVidia Battery Boost tool to detune the 980M or just flipping over to the integrated Intel graphics since honestly they're better at saving power.  It's not even a battery life issue, it's an issue that the battery wattage just can't feed the card.  

It's still pointless with where battery technology is at.

Don't know, I'm not really a fan, but then again I don't really like CS any more, the community behind the game for the most part are horrible. I think that reddit does it just fine already, there is always PC gaming on our forum, I don't really see too many posts about the game even there mostly just people looking for a group to play with. 

5820K
 
Clear upgrade path (if needed) to the 5960X with 40 PCIe lanes.  Or DDR RAM would be usable on a Skylake if you go that route later, although I can't imagine why you would need to.  A much more mature overall ecosystem around the X99 chipset.  

Yea there are already games out there that already need that much RAM, so with an eye on the future I'd also recommend to go with 16 GB

Brand new, but I bought it off Amazon and often they'll just swap it out and save me the hassle of the ASUS RMA.  So I shall hope.  
 
Right now I'm just thankful that 5690Xs don't have pins.  At the very worst case if both Amazon and ASUS go with "No, you must have bent that pin, your problem."  it's a much cheaper fix than a new processor.