Why don't you just sign up for Spotify Premium for 30 days free, then cancel on the 29th day.
Download a couple of Playlist that you like, then you're all set
after the 30 days it's $9.99 a Month and can be used on Multiple devices
Many sites convert youtube to mp3 and then you could simply copy them to your phone? Or I've used tubemate and mp3 video converter on my phone to do it directly