Right now I have a wireless USB adapter. It's connected to my PC and
picks-up my friend's wireless network (w/the passwords) and I have
access to the internet on my PC.

But I need another device I think:

I want to be able to join his wireless network and have a router with
several ethernet sockets so I can connect my PC and additional
internet devices like another PC or an internet phone so:

internet <--> my friend's wireless network <--> ME and I have a bunch
of ethernet sockets to use.

What device should I buy? What is it called? I want to join a wireless
network and then have several Ethernet RJ-45 sockets for devices to
connect to the internet.