You can find Bobby Fisher's bio in the composers/authors/artists section at the GIA website. www.giamusic.org
Bobby is probably best known for his children's music, his workshops at liturgy conferences, and for his guitar playing. (From what I understand, the contemporary composers for GIA and OCP love to have Bobby play the guitar for their recordings or to join them when they are giving concerts.)
I have no idea if the Ziggy Stardust listed as a composer for this particular psalm is David Bowie or not. It could be a pseudonym for someone else or it could be that Bobby borrowed enough of the words from some composition of David Bowie's that he needed/wanted to give him credit.