I'm not sure about terminating narrow SCSI devices on a wide bus.
I'm running a wide device in the middle of a narrow SCSI bus here, and it needs
termaination enabled, even though it's in the middle of the chain.
Acill is correct in saying the best way to terminate a wide bus it to have an
active 68 way terminator at each end of the chain.
Though the CDrom problem sounds like it's not mounting CD0:
The CD0 file needs to be in Devs:DOSdriver
You probably worked out how to set SCSI ID and SCSI device inside CD0
Try booting with no startup and type "mount CD0:" and see what happens. You
might need to execute binddrivers first for it to work.
If working correctly, when you type "info CD0:" it should return something like
"no disk present", unless there is a disc in the drive.
Failing that, run Snoopdos before typing "mount CD0:" and see what's going on.