This is what i mean by "controlled." You can see the original keyboard has it own usb and the slider also has its own.
When you look for left sided mechanical keyboards you find this.
I don't want that. I want the arrow keys on the right side and the numpad on the left. You can obtain this with a detachable numpad but most of the reviews complain the numpad keys not registering due to a poorly designed layout.
Now to the volume slider. I'm a huge music geek and I love the feel of the Slide Potentiometer. Also because I'm a music geek I have all 10 usbs on my motherboard used. I've tried using numerous hubs as you've mentioned before and due to that many usbs being utilized + the hub things didn't function properly. This is why I want to keep it to 1 usb.
I typed in Arduino keyboard and most of them yield pictures like this.
This makes me think that the Arduino will pretty much be maxed out just due to the keyboard wires.
I just typed in Ardiuno slider and yielded this.
Can you daisy chain Ardiuno and still only use 1 usb? If that is the case then I could easily use multi boards.