Hey there welcome to wiichat and enjoy your stay.
-You can surf the net with the Wii as well connecting the DS to the Wii later on.
-Yes, you need a modchip to play backup games.
-The must have game is Zelda: Twilight Princess (my opinion).
-Some games use the wiimote for driving, such as Excite Truck to some extent.
-If you plan on having friends around a lot then you need more wiimotes to enjoy all of the games properly.