Does it really say that somewhere?
I used a couple cd-rom SCSI drives on my classic II and never saw any problems.
Sure. I had it running 7.5.3 and later 7.5.5 with a really old tray load 1x CR-ROM and also a Apple CD 300.Do you remember version of OS supporting your configuration?
My problem is about 7.1 - maybe this is reason of troubles