Very important question. Any just how many additional USB ports on the MB?
The motherboard has 2 USB2 ports on the back and (as far as I can see) no additional headers on the motherboard.
I
believe the chipset should have 2 SATA3 ports, but I haven't got the drives to verify all the ports quickly. If you know a linux command to list all ports and their speed I'd be happy to run it for you.
The PCI slot is version 2. dmidecode lists it as PCI Express x16, but I'm a bit doubtful because the C600 chipset does not mention x16 support.
I've been running two of these systems from a USB stick and so far they have behaved very well. But if you need extensibility they may not be your best choice.