USB3 ports are backwards compatible with all USB devices, they are the blue coloured ones and your external sound card will work perfectly fine. There are no 1.1 ports on that board, it says 2.0/1.1 but there are only USB 2.0 and USB 3.0 ports, Black ones are USB 2 and blue is USB 3.
For your iTunes problem, right click some empty space in your taskbar move to toolbars and check iTunes.
I got the Native Insturments Audio 2, and on usb 2 the sound quality is worse than 3, but on 3 it crackles alot and I have dropouts.
I did exactly that so many times, and it will not ever let me check itunes, I press it and nothing happens. Nothing. At all.