USB 1.0, 2.0 n now 3.0...
As what I know the USB head consists of 4 wires. Can anyone explain:

1. Wat are the 4 wires and their functions?

2. most importantly, how does these wire transfer data?
( I mean like is it really it transfer in binary voltage pulse form to represent a signal?Im trying to use the basic analogue communication mindset, signal and freq stuff... )
( If so, if the signal is distorted, wouldn't it be transferring wrong data to the other terminal? Taking a video as example, if the signal is distorted, then wouldn't it be like watching weird things in the video?. )

3. wats the main difference of USB 1.0 , 2.0 n 3.0 apart from speed transferring?

All your questions and then some are answered at Wikipedia: Universal Serial Bus. The external links section of the article has links to the USB Implementer's Forum where the actual specifications can be found for each version which cover all the nitty gritty details.