Yeah, thats one of those PowerLAN devices. I personally use a setup from Devolo.
Is it faster than conventional Wifi? Not automatically. Your internet is jsut as fast as the contract with your provider says. However, the further you get away from the router, the worse the Wifi signal gets, so yes, Wifi does get slower the further you are away from the router. Metallic doorframes, walls and microwaves can really cut down your Wifi signal to non-existance. That can still happen when using LAN or PowerLAN, but the impact is
significantly less noticable. If you play any sort of online games then LAN or PowerLAN really give you an advantage. Nothing worse than playing with high ping.
PowerLAN: Im really not a networking expert, and it can vary depending on the manufacturer so dont count on me. The basic idea is this:
1) You need at least 2 powerline adapters (such as you linked them).
2) The first adapter goes into a socket near your router. You connect the router with Adapter 1 using a LAN cable. Thats a mandatory setup. It will not work without this.
3) The second adapter however, you can place it wherever you want. Place it in a socket near your computer and connect your computer with the second adapter using a LAN cable. (Just like with the 1st one).
4) The 2 PowerLAN adapters then communicate with eachother and send the packets from the router to your PC across a the low frequency power cables that are found in every home.
Note: The maximum theoretical speed of these PowerLAN adapters is between 500 and 1200 mb/s, which is about 5x or 12x more than the fastest internet lines. I think Ive seen a 300 mb/s contract once here in Germany, but it doesnt get any faster than this. I only have a 16 mb/s line here, which is quite bad.
That means that it will be another 10-20 years until internet providers even offer the bandwidth that would even closely max out the maximum capability of these PowerLAN adapters.
Anway, if you pay for a 16 mb/s line then your connection is only 16 mb/s fast, regardless of the theoreticall speed of these adapters.
PS:
I dont know how much you know about all that stuff, so no pun intended if you know all that already.