WNDR3300 netgear router questions

Hello everyone, I recently received the router described in the title. I have set it up but I have a few questions.

1) When searching for a wireless connection for the router, two seperate connection pop up, an 11n one and an 11g one, what is the difference, and which would be best for say an xbox 360 network adapter?

2) On the settings page of my router I can customize a few things, I want to set it up to get the fastest possible connection obviously but im a bit confused at the settings so I left them at a default, but not sure if I should change them. Here are some of the options it gives

Under MODE- Up to 270Mbps at 2.4GHz
Up to 270Mbps at 5Ghz & 54Mpbs at 2.4GHz (this is the default)
Up to 130Mbps at 2.4GHz
Up to 130Mbps at 5GHz & 54Mbps at 2.4GHz



Under 11n - 36/5.180GHz
44/5.220GHz (this is the default one)
149/5.745GHz
157/5.785GHz

Under 11g- Auto (This is the default)
01/2.412GHz
02/2.417GHz
03/2.422GHz
04/2.427GHz
05/2.432GHZ
06/2.437GHz
07/2.442GHz
08/2.447GHz
09/2.452GHz
10/2.457GHz
11/2.462GHz

Should I leave them as default or is there a setup someone could help me with. Thanks for any help in advance.