Hi. There are lots of spare bays. However, there is no extra cabling. I asked Zoostorm for advice. They told me to buy a HD USB caddy and transfer the data Very helpful. They still have not answered my question on how to expand when there is no power cabling. I presume they never will because you can't. I'm guessing help will only come from Zoostorm before you pay them any money. So, I'd get written assurances before buying or go to Currys
Yes , absolutely, I cloned the drive that came with it onto an SSD drive and added another 2.5 inch drive, so plenty of space but you will need to buy both a power splitter and data cable for the new drive ( there are 4 sata ports internally 2 x 6mbps and 2 x 3 mbps) so juggle them around as necessary.