There is No SD card slot in the Fusion Sport or any 17 Fusion that I'm aware of.
Usb ports can be used to charge phone tablet etc. Charges my phone very fast and are found in a more convenient location than the 12v outlet. At the speed my phone charges connected to the USB they must be set up for this with a higher amperage than just a typical media only setup.
I have found some USB drives will work for playing music, others won't. I don't know why or know how to tell without trying unfortunately. I first tried an older SanDisk usb drive that worked in my 2011 Malibu and it didn't work. Bought a SanDisk ultra fit(physically tiny) and it works fine, no problems unlike cockerdogs experienced.
Sync also recognizes my phone is connected via USB for use as a media drive, Android auto(haven't tried yet), etc.