Free music download for iPhone?

My computer is messed up so I can't use my iTunes playlist thing to put music on my phone. Is there like an app or something that I can download to songs to go into my music? For free?

What should i do erase this iphone and sync with this itunes library?

I'm trying to get ringtones and when I go to "tones" my "sync tones" was off so I click the box and it says " the iphone "alexis" is synced with another iTunes library do you want to erase this iphone and sync with this iTunes library" will that delete all my music and contacts and pictures and apps? What will it to? I have a new iTunes and i've bought stuff on it so does that mean it will switch to my cupiecake1221 one? My old one was iluvmom1221 so would it just switch to the one i'm using now? What will it do!

Best underwater camera or case?

I'm looking for a high quality underwater camera/iPhone 4s case to go snorkeling and swimming with. I mainly care about how clear the photos are, I'm hoping to find something that produces crystal clear quality. Also, it needs to be under 100$.