How to stop iTunes doing this?

So basically I have 2 laptops (one I use for work, one for everything else.) On one of them I had over 484 songs on my itunes. On the other I have a much smaller playlist of my favourite songs (around 18). I did have my iPhone synced to the 1st laptop with 484 songs, but want to erase all of them off of my phone, and sycn with the 2nd laptop with just my favourite songs. (it is of course the same iTunes account.) It's only 18 songs but so far it has taken over an hour on stage 3 of 6 "transfering purchased Items from ____'s iphone". I don't want the items on my iPhone transferred onto this iTunes on this laptop! How can I stop this? All i want to do is add 18 songs onto my phone and erase all the rest but I can't work out how

How to restore my old OS on my iPhone?

I backed up my phone the other day and without asking me, the phone installed the new OS. It's the 4s It also deleted all of my apps that I have installed. It will not allow me to check the weather nor log my resents on my call list. I'd like to just revert back to the way it was.

I know, I should have gotten a better phone than the iPhone but I have what I have for now. I just want to go back to when it worked better until I can get something better.

If I can't restore the original OS, how do I at least restore all of my apps?

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Again, Hi2mic, How do I restore the apps which should be backed up?
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IPhone 5c randomly taking my credit?

I just topped up £10 and when i went to double check my credit i only had £9.31 anyone know why it is randomly taking my credit?

Added (1). How am i using my phone too much when i bought it 3 days ago and i only use it for texting and listening to music. The problem is that it takes credit when i don't text or do anything on it