Will i lose all my music when i sync iphone to new lap top?

A couple months ago my itunes on my PC freaked out and i never synced my iphone to it again because i didn't want to risk losing my music. Now i have a macbook and want to put my music that is on my iphone onto the itunes on the macbook. How do i do this?

How to zoom in and out the screen on an iPhone 4?

First of all, I don't even know how I keep zooming the screen. Then, the screen gets stuck with everything magnified. Usually, I can slide the screen around to turn it off, but even the off slider is so huge that I can't turn it off.

Obviously, I'm not very tech-smart. (haha)

How do I get the screen back to normal size? How is it zooming, anyways?

IPhone 5 Problem with Messages?

So I recently got the iPhone 5 and it just started doing this today. Whenever I get a text or iMessage, I get two identical messages. Is it because one is for iMessage and one is for Text messages? Cause my friend does not have an iPhone, and yet I get two messages from him.