The install is almost the same as x86, except in ppc architecture there in no grub, ppc use yaboot and works slightly different. Yes, you can install macosx again without problems, only you must delete existing partition.
May be you want to use both os (macosx and linux) in the same machine, in that case is better to use macosx to partition disk, then install macosx and then install Fedora.
Pietro Pesci Feltri
PowerBook 15" G4 and
MacBook Pro 17" Intel Core 2 Duo
Intel I5 Desktop