What does syncing my iPhone mean? - 1

I have a 13 inch Macbook Air and an iPhone 5S with updated software. I want to put a ringtone onto my phone. I already have it set up, but when I want to put it onto my phone, it wants me to "sync" it. It says that it's going to clear the iTunes library on my phone, which has music my Macbook doesn't have. People online say that it's just going to add the songs from my Macbook, and not replace the ones on my phone. Which is right?

Iphone 5 won't let people leave messages when they call?

I've had an iphone for a couple years now and am just now realizing people are unable to leave a message. When they call, all it says "This is Verizon wireless. Your call can't be completed as dialed. Please hang up and try again." I checked an my voicemail is set up and everything, but it still does not work. Any suggestions?

How to break an iPhone to get a new one?

My phone has some nicks and scratches on it and I want to get a new one. Is there a way I can break it and get a new one, that is covered by the Apple warranty?

Where to download music for free?

I had movie box before but it keeps crushing when I open the app so where can you watch movie for free without signing up and paying using your iPhone?

Unlock an iPhone 5c with Brazilian SIM card?

My bro gave me an iPhone 5c that he found 2 years ago, which he couldn't unlock. It was some brazilian tourist I assume since the last country in the settings shows Brazil and the SIM card says VIVO chip, which I have found is Brazilian. I have tried changing the DNS server on the phone but nothing works. I also tried calling 112. Can anyone help?