1920 x 1080 is the resolution I play at. I, uh, don't know how to overclock.
I have no idea what CUDA is so I don't use it. As far as an SSD goes I tried installing one once but it didn't work right.
I've always bought the parts for my PC and had my brother build it for me. For the one I use now I bought it from Maingear.
If I were to get a new graphics card should I get the Nvidia Titan or a Nvidia 600 series?
To get a worthwhile upgrade from the 580 you'd pretty much have to go Titan.
But honestly your system is probably fine until the next series 7xx comes out.