Changing fonts in Rock Star free & premium versions?

Hi Support Folks, A couple of questions please re: the Rock Star theme, both the free version and premium. 1) Can you change the fonts in the Rock Star free demo, as well as the premium version, and if so, how? 2) My website person also created something called a "child theme" for the Rockstar free version website, to assist as a backup to preserve any modifications. If I upgrade to the premium Rockstar theme, will the child theme be preserved or lost? My url is http://www.musiciansontherecord.com/ Thank you, David