A good quality skin should be cleanly removable, so unless the phone skin is much cheaper, there's not much benefit to practicing on the phone first. I wouldn't worry so much.
Also sorry for randomly info-dumping that wall of text, oh god. I tend to do that when I'm obsessed with something haha ^^"
As a whole, I enjoyed the music from Deemo most. Other than that, I love playing rhythm games to Monstercat Dubstep, DnB and Drumstep songs, but they're usually not officially in any game (except Just Shapes and Beats but I wouldn't call it a rhythm game).