Go here. Most of your questions can be answered there. Now, since your new, I'll answer your questions:
1. Yes, Wii will play all GC games, but only with the GC controller. There are four GC controller ports on the Wii aswell as 2 GC memory card ports.
2. Both the nunchuk and wiimote (wii remote) have the same motion sensing abilities. The only difference is the wiimote has the extra ability to be used as a pointer, like in a first person shooter you point it at the screen to shoot, while the nunchuk does not.
Hope that helped and hope you have a nice time on this site.