1. I would pick up a Waivebird (GC:controller).
2. Wiiplay (game) for the free Wiimote.
3. A Nunchuck so that you would have and extra set for any guests that come over.
4. Also a 1 Gig SD card. You don't need the official Wii one. Just pick up a SD card at OfficeMax or a camera store.
Accessory wise that's all I would get at the bare minimum.
5. As far as a router goes. I just use my AT&T U-verse router that came with my broadband connection. I think it is a 2wire running 802.11-N, any should work though.