yes Roger Federer is better than Rafael Nadal
I'm not familiar with Modely. Who sings it?
 i'm sure the songs were selected from an already established ... If you're not familiar with a song you kinda need the vocals to learn how
Very interesting. It sounds like you're into singing. You might look into 30 Day Singer. It's an online singing course that could help you hone your vocal technique.
Christina Aguilera's Masterclass. you might look into 30 day singer
So you're a Christina fan? Very cool! Her first album came out on RCA. She had a string of low-performing albums in the early 2010s, though.