extremescouter

For that, and some room to upgrade, I would probably go with a 650w power supply. I personally use Corsair for their reliability, but I think it is essentially personal preference for the brand.

I essentially had the same requirements of a system I built last summer. I would definitely look into this: http://www.tonymacx86.com/344-building-customac-buyer-s-guide-april-2013.html. My suggestions would be with heavy music production, you might want to think of upgrading to an i7 3770k, so you get the benefits of hyper threading. Go with a cooler master hyper 212 for the cooler, and you can easily get good temps to overclock. As long as you dont need thunderbolt, the Gigabyte UD-5h is a great option, with great compatibility and features. With light gaming, many people agree that a Nvidia GTX 660 is the best fps per dollar gaming card on the market, and it works well with hackintoshes. Other than that, probably 16gb of ram for the music production. 
 
Also, Haswell is supposedly coming out soon, so you might want to think about it. However, it will probably take awhile for Apple to integrate compatibility with OSX, so you probably wouldnt be able to get the compatibility of a hackintosh by this summer. 

Ok, heres a new link: http://www.tonymacx86.com/351-building-customac-buyer-s-guide-may-2013.html
 
It depends on what applications you will be using. For me, I will routinely have photoshop, mail, and safari open at the same time, and use up my 16 gbs of RAM. I am not sure how much RAM your music software uses, but it seems like the extra ram could be helpful with 30 tracks open at a time, and you will definitely see a difference between 8 and 16 gb. 

Yeah, but the problem is this card has a whole riser card on that side to fit all of the power management to effectively overclock the CPU. Thats part of what makes that board so great, in that you can overclock it just as much as a full ATX sized motherboard. 

It really depends on what you're planning to do. A great way to decide would be to go on Linus' Youtube channel, and search benchmark showdown. There, you will be able to see a variety of benchmarks for any game you plan to play. He has a variety of price points, and you can see what fps you will get if you buy a certain card, and play a certain game. 

You said that this will be a gaming rig, so are you gaming off of the HD 4000 graphics?
 
While you may be future proofing, there could be other options out there for a case, as well as the Samsung 840 pro. Replacing that with a cheaper ssd, and a different case, you could probably save $100+, which you could easily spend on other areas of your build. 

If I had enough money, Id buy that just for the cup holder.