laptop usb hookup

Is it possible to share information with my headunit (Kenwood DNX7100) from my laptop through the USB port on the Kenwood and the USB port on my laptop?

Not likely. The USB port on most heads is "input only", meaning it is a reader, for external storage devices, only.

Kenwood may have a way of using it, but they only use it for diagnostics or firmware updates. You probably wouldn't be able to get a hold of the software to make them talk, either. If you'll notice, also, the ports are the same - i.e. USB A, and with the exception of USB network interface cables, I have never seen a USB cable with two USB A ends.

What are you trying to do, that would make you ask this question, anyway?

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

was trying to see if there was a way to use the USB port to have the head unit pull music from the laptop HD

Nope... that's DEFINITELY not going to happen. The hard drive inside your laptop is invisible to every outside device, without network layers - i.e TCP/IP - a network protocol, NOT a USB protocol. Let alone the fact that your Kenwood deck will not have network layers of any sort in it, to talk to Windows, and allow Windows to share the drive with your deck. Again, I also mention the fact that you'll never find a USB-A to USB-A cable... They don't exist, that I have ever seen.

The internal hard drive will remain forever invisible to your head unit.

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."