streaming a full song or play half?

Dear all,

i am trying to have a site built that will help the unsigned music artist to sell their songs.the problem is the programmers i am using don't really know much about music streaming,if i do the wrong choice it could cost the life of my future business,i hope someone can help me please,here are my questions:

1)i dont really understand what streaming is about,if i have an mp3 track of 3 mb,the programmers will create a javascript code that will play only half of the file,this mean i am using only 1,5 mb bandwith for that song...can stremaing do better than that?could i play the full music of 3mb for 1 mb bandwith?
please explain because i am lost:!}, thank you.

2)how does streaming works,do i have to encrypt the file first or can a streaming player just stream a music from the original file without heaving load on the processor?

3)could you explain to me how this process of uploading a song on a website as an mp3 and then when you press play on that site you can hear the same song on a streaming format?

thank you very much all,i cannot have any help from the programmers ,you are my last chance.


bambinou