Graham,
Yes, the 3K has a single USB port, however, you can purchase splitter devices for unbieveably low prices at
www.cyberguys.com Yes, you can use an external hard drive as well as a Smart Media Card, and both can be operational at the same time. It's an amazing machine and I sincerely believe that most folks that have purchased the 3000 will be happy with the keyboard.
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)