Yes, this Plipbox offered here allows you to connect to the Internet without any additional requirements. You don’t need anything else. I ship the device driver on a floppy disk together with the Plipbox. I can offer you a power supply unit if you need one (DC 9V / European connector) for additional 4 USD. But you can alternatively power the Plipbox by a normal USB charger (e.g. from a cell-phone or mp3-player). You will see these two options on the rear side of the Plipbox on the pictures (where the Ethernet socket is); there you find a round barrel power jack (DC 9V) and a USB socket (you can use one or the other for powering the Plipbox).
On the website of lafalla, there's a nice tutorial to set up the tcp/ip stack on the Amiga. It's easy. I can support you if you have problems.
