Questions difference four memory channels, or two channels of memory

[username_48]

I want to ask questions What is the difference between the 4 channels like CPU 3960K memory
And two memory channels like CPU 3770K ?

One. How do I know if the two channels of memory is enough for me or I need four memory channels ?

Two. 3960K processor
Max Memory Bandwidth
51.2 GB / s What this means ?
I'm currently using a processor with two memory channels that come up occupancy 4.5GB of 8GB
Does this mean I do not need 51.2 GB

Three. Is four channels give working speed of memory greater than - 2 memories and how it will be expressed ?
For example a game takes me 1 million Bit from memory, the mother with four channels of memory is decreased by 30%, for example

Four Is Win 8 64 BIT handles memory better?
(from win 7 64)

 

[username_48]

English is not native language, something is not clear on the question?