I always like Bozzio's part of the Devil on FZ's "Titties and Beer".I couldn't see him in Duran Duran,he was a classical trained musician who was a madman on the drums.Warren Cucurillo as far as I know was someone who frequented Frank's shows,wishing he could join his band,until he met him back stage and Frank gave him an audition eventually and thought he was good enough .He had to be good because Zappa was known for being particular and would fire you in a minute if you couldn't play the way he wanted.I think it was short lived ,though.
I read somewhere that Cucurillo had posed naked in some hard-core porn mag and that the Duran members did not like that at all, thus cutting him off the lineup a while back.