Hello
The 860K is one of the APU-chips but with the integrated graphics removed. I guess that + the GTX 750Ti is a better purchase than the APU-unit since the GTX 750 Ti is more powerful.
With that said for about the same money you get an Intel Pentium G3258 which would be a better processor:
http://www.techspot.com/review/1017-best-budget-gaming-cpu/
The Intel-chip is more powerful / core but only has two cores, the AMD chip is more powerful (in Passmark) using all four cores:
http://cpuboss.com/cpus/Intel-Pentium-G3258-vs-AMD-Athlon-X4-860K
The Intel chip however can be overclocked and by quite a bit likely removing that difference even using multiple cores. It's also a lower (electricity and heat) power chip from the beginning so you can over-clock it and still likely use about as much electricity and have a similar amount of heat to get rid with.
According to the test above the 860K could be over-clocked as-well but regardless the G3258 most often beat the 860K both in stock clock and over-clocked.
So the G3258 is the better alternative for the build.
Regarding the RAM using two modules will give better bandwidth but use up two slots limiting expansion capability in the future, but regular motherboards usually have four slots and I guess it's unlikely you'll want to get more than another 2x8 for a total of 24 GB of RAM in the future anyway? So it doesn't matter. I suggest using two modules.
You can lose the sound-card with minimal disadvantage. The CPU-cooler is better than a stock-cooler and better for over-clocking but if you want money for something else you can remove that and use the stock-cooler as-well.
The graphics card is decent and using G3258 + GTX 750 Ti will likely give you a decent low-end build which will allow you to play many of recent / current titles at lower quality and possible resolution at playable frame-rates.
Personally I don't use an optical drive, you could save money there to but will need one or an USB-drive for OS installation. You could likely borrow it from a friend or older computer though? Similarly if you have an older computer what about using that case and power supply unit?
You could save additional money by not purchasing the OS. I assume the standard-solution for how to handle a computer without a purchased OS isn't allowed to be discussed on the forum but if you'd be ok with playing games which run on Linux like CS:GO, DOTA, Civ V, X-Com you could install SteamOS / any Linux distribution and Steam and play like that and save the money for Windows. Most of the games won't run on Linux though. Witcher 3 will supposedly come for Linux. Don't seem like Fallout 4 will. Guess not for Battlefront either.
So yeah..
With the money saved from an optical-drive, the sound-card and the CPU-cooler you could get an i3 processor instead of the G3258. Those don't have unlocked multipliers so you won't be overclocking it, on the other hand it supports hyper-threading and is likely a better processor than the G3258 even when overclocked.
If you could use an old case and/or PSU or ditch Windows you could also had upgraded to the GTX 950 or R9 380.
The i3 isn't perfect either but it's somewhat better than the G3258 which is quite a bit better than the 860K for many of the games out now at-least.
Good luck with your build and gaming regardless of what you choose
(If you want to chat I'm on Steam as aliquise.)