When installing Mac OS 9 on an iMac G4, compatability depends on the model of iMac that you are trying to install on. Earlier models (2002) can run 9 while anything from 2003 can't (But I'm sure you already knew that). Make sure that your model is compatable before trying to install. As for the speed, it could be the drive, disk, or any number of things. Try installing from another mac, or an external Firewire drive to see if there is any difference. As for audio, the iMac should have a standard 3.5 mil. jack. The port that you are refering to was originally designed for a pair of Apple Pro Speakers (H/K) that shipped with some of the iMac G4s.
