Been here? www.google.com Good place for homework related questions.
1) read here > http://www.juniper.net/techpubs/en_US/junos-space-apps12.3/network-director/topics/concept/wireless-interference.html - also read up on attenuation.
2)the 'n' standard is fastest out of your list. Being the fastest makes it the obvious choice for a household. Problems as with any wireless tech is anything that will be a disrupt the connection - solid walls, high emr devices etc.
3)most devices cover all standards anyway except for rising uptake of the newer, faster ac standard.
People hate on Wikipedia a lot but 99% of the stuff I have learned on Wikipedia has been 100% true, especially in the area of networking. It's amazing what you can learn just by messing around with some virtual machines on a little laptop.
Hey I'm just curious, what is "Super G"? Is that an actual thing? I saw it as a settings option while helping a friend configure an EXTREMELY old router (about 4 years old)