What is the best format to use for music? Can I use more than one, wma and mp3?
mp3 is more universal; I don't believe wma is supported in Jelly Bean.
See page 44 of your manual for supported file types:
https://motorola-global-portal.custhelp.com/ci/fattach/get/603219/1363365632/redirect/1/filename/...
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