and a four-port fast ethernet hub.
Using a crimping tool to attach the RJ45 plugs is like many things - easy when you know how, but tricky at first. Spend time preparing the cable ends, and make sure you cut them all exactly the same length before attemptingto insert them into the plug. Most first-time networking problems are associated with cabling errors.
Yes, you can get network socket boxes, just like BT boxes.
If, as you say, you move house quite often, why don't you go for a wireless network? The initial expense will be a bit higher, but you can simply move the hard ware with you when you go - it couldn't be easier to set up, and the network will work very well.