There is only one in the pack so you would need two of these surely?
Sorry wasn’t clear. On this particular model no, as the ports as limited. So it would be 100mbps per port max regardless of whether you added a switch. A good example of a rare 500mbps powerline with gigabit ports is the Netgear av500 gigabit (not the old standard one with 100mbps ports). It would allow you to utilise the full 500mbps if connected to a gigabit switch. In reality, I doubt 90% of users would have a real work use for gigabit over standard Ethernet.
I'm still confused. So even though the port on the plug is only 100Mbps, you can still get 100Mbps each on a 5 port switch connected to one of these ports?
What you using them for
Yep, only the one in the "kit" according to a couple of the Q&As.